GRAF Graf Industrial Corp

ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS

This document, which forms part of a registration statement on Form S-4 filed with the SEC by Ouster, constitutes a prospectus of Ouster under Section 5 of the Securities Act of 1933, as amended, which is referred to as the Securities Act, with respect to the shares of common stock of Ouster to be issued to Velodyne stockholders pursuant to the Agreement and Plan of Merger, dated as of November 4, 2022 (as it may be amended from time to time), by and among Ouster, Velodyne, Merger Sub I and Merger Sub II, which is referred to as the merger agreement. This document also constitutes a joint proxy statement of Ouster and Velodyne under Section 14(a) of the Securities Exchange Act of 1934, as amended, which is referred to as the Exchange Act. It also constitutes a notice of meeting with respect to the Ouster special meeting and a notice of meeting with respect to the Velodyne special meeting.

Ouster has supplied all information contained or incorporated by reference into this joint proxy statement/prospectus relating to Ouster, and Velodyne has supplied all such information relating to Velodyne. Ouster and Velodyne have both contributed to the information related to the mergers contained in this joint proxy statement/prospectus.

You should rely only on the information contained in or incorporated by reference into this joint proxy statement/prospectus. Ouster and Velodyne have not authorized anyone to provide you with information that is different from that contained in or incorporated by reference into this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated December 8, 2022, and you should not assume that the information contained in this joint proxy statement/prospectus is accurate as of any date other than such date unless otherwise specifically provided herein.

Further, you should not assume that the information incorporated by reference into this joint proxy statement/prospectus is accurate as of any date other than the date of the incorporated document. Neither the mailing of this joint proxy statement/prospectus to Ouster stockholders or Velodyne stockholders nor the issuance by Ouster of shares of its common stock pursuant to the merger agreement will create any implication to the contrary.

This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction to or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

Unless otherwise indicated or the context otherwise requires, when used in this joint proxy statement/prospectus:

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QUESTIONS AND ANSWERS

The following are some questions that you, as a stockholder of Ouster or a stockholder of Velodyne, may have regarding the mergers and the other matters being considered at the special meetings of each company’s stockholders, and brief answers to those questions. You are urged to carefully read this joint proxy statement/prospectus and the other documents referred to in this joint proxy statement/prospectus in their entirety because this section may not provide all the information that is important to you regarding these matters. Additional important information is contained in the annexes to, and the documents incorporated by reference into, this joint proxy statement/prospectus. You may obtain the information incorporated by reference in this joint proxy statement/prospectus, without charge, by following the instructions under the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus.

In order to complete the mergers, among other things:

Ouster is holding a special meeting of its stockholders, which is referred to as the Ouster special meeting, to obtain approval of the Ouster share issuance proposal. Ouster stockholders will also be asked to approve (i) an amendment to the Ouster charter to allow Ouster, (a) to have the option to effect, separate from and following the closing of the mergers or (b) if the merger agreement is terminated, to have the option to effect, (1) a reverse stock split of Ouster common stock at one of six reverse stock split ratios, one-for-five, one-for-six, one-for-seven, one-for-eight, one-for-nine and one-for-ten, with an exact ratio to be determined by the board of the combined company following the closing or the Ouster board, as applicable, and (2) if and when the reverse stock split is effected, a corresponding reduction in the number of authorized shares of Ouster common stock by the selected reverse stock split ratio, in the form attached to this joint proxy statement/prospectus as Annex B, which proposal is referred to as the Ouster reverse stock split proposal and (ii) the proposal to adjourn the Ouster special meeting to solicit additional proxies if there are not sufficient votes at the time of the Ouster special meeting to approve the Ouster share issuance proposal or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Ouster stockholders, which proposal is referred to as the Ouster adjournment proposal (approval of which is not conditioned upon approval of the Ouster share issuance proposal or on completion of the mergers).

Velodyne is holding a special meeting of its stockholders, which is referred to as the Velodyne special meeting, to obtain approval of the Velodyne merger agreement proposal. Velodyne stockholders will also be

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asked to approve (i) on a non-binding advisory basis, the compensation that may be paid or become payable to Velodyne’s named executive officers that is based on or otherwise relates to the transactions contemplated by the merger agreement, which proposal is referred to as the Velodyne compensation proposal and (ii) the proposal to adjourn the Velodyne special meeting to solicit additional proxies if there are not sufficient votes at the time of the Velodyne special meeting to approve the Velodyne merger agreement proposal or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Velodyne stockholders, which proposal is referred to as the Velodyne adjournment proposal.

Your vote is very important, regardless of the number of shares that you own. The approval of the Ouster share issuance proposal and the approval of the Velodyne merger agreement proposal are conditions to the obligations of Ouster and Velodyne to complete the mergers. None of the approvals of the Ouster reverse stock split proposal, the Velodyne compensation proposal, the Ouster adjournment proposal or the Velodyne adjournment proposal are conditions to the obligations of Ouster or Velodyne to complete the mergers.

The Velodyne special meeting will be held at 5521 Hellyer Avenue, San Jose, CA 95138, on January 26, 2023 at 9 a.m., Pacific Time.

To participate in the Ouster special meeting, you will need the 16-digit control number included on your proxy card or on the instructions that accompanied your proxy materials. The meeting webcast will begin promptly at 9 a.m., Pacific Time. We encourage you to access the meeting prior to the start time. Online check-in will begin at 8:45 a.m., Pacific Time, and you should allow ample time for check-in procedures. If you hold your shares through a bank or broker, instructions should also be provided on the voting instruction card provided by your bank or brokerage firm. If you lose your 16-digit control number, you may join the Ouster special meeting as a “Guest,” but you will not be able to vote, ask questions, or access the list of stockholders as of the record date.

For Velodyne stockholders, if you choose to vote your shares in person at the Velodyne special meeting, please bring required documentation in accordance with the section entitled “The Velodyne Special Meeting—Attending the Velodyne Special Meeting” of this joint proxy statement/prospectus, with respect to the Velodyne special meeting. The use of video, still photography or audio recording at the Velodyne special meeting is not permitted. For the safety of in-person attendees at the Velodyne special meeting, all bags, packages and briefcases are subject to inspection.

Even if you plan to attend or virtually attend your company’s special meeting, Ouster and Velodyne recommend that you vote your shares in advance as described below so that your vote will be counted if you later decide not to or become unable to attend the applicable special meeting. With respect to the Velodyne special meeting, shares held in “street name” may be voted in person by you only if you obtain a signed legal proxy from your bank, broker or other nominee giving you the right to vote the shares.

For Ouster stockholders, if you do not return or submit your proxy or vote at the special meeting as provided in this joint proxy statement/prospectus, it will have no effect on the Ouster share issuance proposal or the Ouster adjournment proposal. If you are a record holder of Ouster’s common stock and do not return or submit your proxy or vote at the special meeting as provided in this joint proxy statement/prospectus, it will have the same effect as a vote “AGAINST” the Ouster reverse stock split proposal. The board of directors of Ouster, which is referred to as the Ouster board of directors, unanimously recommends that you vote “FOR” the Ouster share issuance proposal, “FOR” the Ouster reverse stock split proposal and “FOR” the Ouster adjournment proposal.

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For Velodyne stockholders, if you do not return or submit your proxy or vote at the special meeting as provided in this joint proxy statement/prospectus, the effect will be the same as a vote “AGAINST” the Velodyne merger agreement proposal, and will have no effect on the Velodyne compensation proposal or the Velodyne adjournment proposal. The board of directors of Velodyne, which is referred to as the Velodyne board of directors, unanimously recommends that you vote “FOR” the Velodyne merger agreement proposal, “FOR” the Velodyne compensation proposal and “FOR” the Velodyne adjournment proposal.

If the mergers are completed, Ouster stockholders’ shares of Ouster common stock will, after the effective time, constitute shares of the combined company. Because Ouster will issue a fixed number of shares of Ouster common stock in exchange for each outstanding share of Velodyne common stock, the value of the merger consideration that Velodyne stockholders will receive in the mergers will depend on the market price of shares of Ouster common stock at the effective time. The market price of shares of Ouster common stock that Velodyne stockholders receive after the mergers are completed could be greater than, less than or the same as the market price of shares of Ouster common stock on the date of this joint proxy statement/prospectus or at the time of the special meetings. Accordingly, you should obtain current market quotations for Ouster common stock and Velodyne common stock before deciding how to vote with respect to the adoption of the merger agreement. Ouster common stock is traded on the New York Stock Exchange, which is referred to as the NYSE, and Velodyne common stock is traded on the Nasdaq Global Select Market, which is referred to as the Nasdaq, under the symbols “OUST” and “VLDR,” respectively. Shares of common stock of the combined company are expected to trade on the NYSE under the symbol “OUST.”

For more information regarding the merger consideration to be received by Velodyne stockholders if the mergers are completed, see the section entitled “The Merger Agreement—Merger Consideration” of this joint proxy statement/prospectus.

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All Velodyne restricted stock unit (“RSU”) awards held by continuing service providers will be converted into an award of restricted stock units covering Ouster common stock (each, an “Ouster RSU award”) with the same terms and conditions as applied to the Velodyne RSU award immediately prior to the effective time; however, the Ouster RSU awards will cover a number of shares of Ouster common stock equal to the product of the number of shares of Velodyne common stock subject to the Velodyne RSU award and the exchange ratio. Each Velodyne RSU award that is not held by a continuing service provider will terminate immediately prior to the effective time for no consideration.

Each share of Ouster common stock issued upon conversion of a share of Velodyne common stock, as described in this paragraph, that is subject to a substantial risk of forfeiture within the meaning of Section 83 of the Code, as amended (“Velodyne Restricted Stock”) will be subject to the same substantial risk of forfeiture and will have the same terms and conditions, including vesting, as applied to the Velodyne Restricted Stock immediately prior to the effective time (“Ouster Restricted Stock”), except that any performance goals applicable to Velodyne Restricted Stock will be deemed achieved at the greater of target and actual performance and, as of the effective time, the Ouster Restricted Stock issued on conversion of Velodyne Restricted Stock that was originally scheduled to vest based on performance goals will be subject solely to the service-based vesting schedule otherwise applicable to the Velodyne Restricted Stock.

All shares of Velodyne Restricted Stock and all Velodyne RSU awards held by non-employee members of the Velodyne board of directors will vest in full and become free of any restrictions, including any risk of forfeiture, as of the effective time and will be treated as shares of Velodyne common stock under the merger agreement.

At the effective time, each of the public warrants and private warrants of Velodyne (“Velodyne Warrants”) will be converted into a warrant to acquire Ouster common stock (“Ouster Warrant”) with the same terms and conditions as applied to such Velodyne Warrant immediately prior to the effective time; however, such Ouster Warrant will cover a number of shares of Ouster common stock equal to the product of the number of shares of Velodyne common stock subject to the Velodyne Warrant and the exchange ratio and will have an exercise price per share equal to the amount obtained by dividing the per share exercise price of the Velodyne Warrant by the exchange ratio. As of November 15, 2022, Velodyne had (i) outstanding publicly traded warrants exercisable for 4,480,425 shares of common stock at $11.50 per share; and (ii) an outstanding private warrant owned by an affiliate of Amazon Inc., exercisable for up to 39,784,213 shares of common stock at $4.16 per share, 50% of which will vest at the effective time.

The mergers will each be treated as a “change in control” or term of similar meaning for purposes of the Velodyne compensation and benefit plans, which determination will result in certain “double trigger” benefits under certain of such plans upon a qualifying termination of employment by certain executives subsequent to the effective time. For more information, see the information provided in the section entitled “Interests of Velodyne’s Directors and Executive Officers in the Mergers” of this joint proxy statement/prospectus.

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In considering the recommendations of the Ouster board of directors, Ouster stockholders should be aware that Ouster directors and executive officers have interests in the mergers that are different from, or in addition to, their interests as Ouster stockholders. These interests may include, among others, the payment of severance benefits and acceleration of outstanding Ouster equity awards upon a qualifying termination of employment. For a more complete description of these interests, see the information provided in the section entitled “Interests of Ouster’s Directors and Executive Officers in the Mergers” of this joint proxy statement/prospectus.

In considering the recommendations of the Velodyne board of directors, Velodyne stockholders should be aware that Velodyne directors and executive officers have interests in the mergers that are different from, or in addition to, their interests as Velodyne stockholders. These interests may include, among others, the payment of severance benefits, including the acceleration of outstanding Velodyne equity awards upon certain qualifying terminations of employment in connection with the mergers. For a more complete description of these interests, see the information provided in the section entitled “Interests of Velodyne’s Directors and Executive Officers in the Mergers” of this joint proxy statement/prospectus.

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A “broker non-vote” occurs on an item when (a) a bank, broker or other nominee has discretionary authority to vote on one or more proposals to be voted on at a meeting of stockholders, but is not permitted to vote on other proposals without instructions from the beneficial owner of the shares and (b) the beneficial owner fails to provide the bank, broker or other nominee with such instructions. None of the proposals currently scheduled to be voted on at either the Ouster special meeting or the Velodyne special meeting are routine matters for which brokers may have discretionary authority to vote, except for the Ouster reverse stock split proposal, which is considered routine and brokers therefore have discretionary authority to vote.

Ouster Proposal # 2: Ouster Reverse Stock Split Proposal. Assuming a quorum is present at the Ouster special meeting, the approval and adoption of the amendment to the Ouster charter to allow Ouster, (a) to have the option to effect, separate from and following the closing of the mergers or (b) if the merger agreement is terminated, to have the option to effect, (i) a reverse stock split of Ouster common stock at one of six reverse stock split ratios, one-for-five, one-for-six, one-for-seven, one-for-eight, one-for-nine and one-for-ten, with an exact ratio to be determined by the board of the combined company following the closing or the Ouster board, as applicable, and (ii) if and when the reverse stock split is effected, a corresponding reduction in the number of authorized shares of Ouster common stock by the selected reverse stock split ratio, requires the affirmative vote of the holders of a majority of the outstanding shares of Ouster common stock entitled to vote at the Ouster special meeting on the Ouster reverse stock split proposal. Accordingly, an Ouster stockholder’s abstention from voting or the failure of an Ouster stockholder not present at the meeting to vote will have the same effect as a vote “AGAINST” the Ouster reverse stock split proposal. We do not anticipate any broker non-votes in connection with this proposal. Approval of the

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Ouster reverse stock split proposal is not conditioned upon approval of the Ouster share issuance proposal or on completion of the mergers. As a result, if the Ouster stockholders vote to approve the Ouster reverse stock split proposal, and if the merger agreement is terminated, the Ouster board of directors, in its discretion, may elect to effect the reverse stock split.

Ouster Proposal # 3: Ouster Adjournment Proposal. The Ouster special meeting may be adjourned to solicit additional proxies if there are not sufficient votes at the time of the Ouster special meeting to approve the Ouster share issuance proposal or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Ouster stockholders. If a quorum is present, the affirmative vote of the holders of a majority in voting power of the votes cast at the Ouster special meeting on the Ouster adjournment proposal is required to adjourn the Ouster special meeting. Accordingly, in such case, an Ouster stockholder’s abstention from voting, a broker non-vote or the failure of an Ouster stockholder not present at the meeting to vote will have no effect on the Ouster adjournment proposal. If a quorum is not present, then either (i) the person presiding over the meeting or (ii) a majority in voting power of the stockholders entitled to vote at the meeting, present in person, or by remote communication, or represented by proxy, shall have power to adjourn the Ouster special meeting. Accordingly, in the case of (ii), an Ouster stockholder’s abstention from voting, a broker non-vote or the failure of an Ouster stockholder not present at the meeting to vote will have the same effect as a vote “AGAINST” the Ouster adjournment proposal.

The Ouster reverse stock split proposal, if approved by Ouster stockholders, will provide the board of the combined company with the flexibility, but not the obligation, to effect a reverse stock split, separate from and following the closing of the mergers and the transactions contemplated by the merger agreement. If the mergers are not consummated for any reason, the Ouster board of directors may still elect to effect a reverse stock split. Even if the Ouster reverse stock split proposal is approved by Ouster stockholders, the board of the combined company may delay or abandon the reverse stock split at any time prior to the effective time of the reverse stock split if the board of the combined company determines that the reverse stock split is no longer in the best interests of the combined company or its stockholders. For further details, see the section titled “Ouster Proposal #2: Ouster Reverse Stock Split Proposal.”

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Velodyne Proposal #2: Velodyne Compensation Proposal. Assuming a quorum is present at the Velodyne special meeting, the approval, on a non-binding advisory basis, of the compensation that may be paid or become payable to Velodyne’s named executive officers that is based on or otherwise relates to the transactions contemplated by the merger agreement, requires the affirmative vote of the holders of a majority of the votes cast at the Velodyne special meeting on the Velodyne compensation proposal. Accordingly, a Velodyne stockholder’s abstention from voting, a broker non-vote or the failure of a Velodyne stockholder not present at the meeting to vote (including the failure of a Velodyne stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the Velodyne compensation proposal.

Velodyne Proposal #3: Velodyne Adjournment Proposal. The Velodyne special meeting may be adjourned to solicit additional proxies if there are not sufficient votes at the time of the Velodyne special meeting to approve the Velodyne merger agreement proposal or to ensure that any supplement or amendment to this joint proxy statement/prospectus is timely provided to Velodyne stockholders. Whether or not a quorum is present, the affirmative vote of the holders of a majority of the votes cast at the Velodyne special meeting on the Velodyne adjournment proposal is required to approve the Velodyne adjournment proposal, and the chairman of the Velodyne special meeting also has the power to adjourn such Velodyne special meeting from time to time. Accordingly, a Velodyne stockholder’s abstention from voting, a broker non-vote or the failure of a Velodyne stockholder not present at the meeting to vote (including the failure of a Velodyne stockholder who holds shares in “street name” through a bank, broker or other nominee to give voting instructions to that bank, broker or other nominee) will have no effect on the Velodyne adjournment proposal.

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Shares in “street name.” With respect to the Velodyne special meeting, shares held in “street name” may be voted in person by you only if you obtain a signed legal proxy from your bank, broker or other nominee giving you the right to vote the shares and bring the signed legal proxy to the meeting. If you choose to vote your shares in person at the Velodyne special meeting, please bring required documentation in accordance with the section entitled “The Velodyne Special Meeting—Attending the Velodyne Special Meeting” of this joint proxy statement/prospectus.

With respect to the Ouster special meeting, if your shares are held in street name through a bank, broker or other nominee, you will receive instructions on how to vote from the bank or broker. You must follow their instructions in order for your shares to be voted. Internet and telephone voting also may be offered to stockholders owning shares through certain banks and brokers. If your shares are not registered in your own name and you would like to vote your shares at the Ouster special meeting, you may visit www.virtualshareholdermeeting.com/OUST2023SM and enter the 16-digit control number included in the voting instruction card provided to you by your bank or brokerage firm. If you hold your shares in street name and you do not receive a 16-digit control number, you may need to log in to your bank or brokerage firm’s website and select the shareholder communications mailbox to access the meeting and vote. Instructions should also be provided on the voting instruction card provided by your bank or brokerage firm.

Even if you plan to attend the Ouster special meeting electronically or the Velodyne special meeting in person, as applicable, Ouster and Velodyne recommend that you submit a proxy to vote your shares in advance as described below so that your vote will be counted if you later decide not to or become unable to attend the respective special meeting. The use of video, still photography or audio recording is not permitted at either the Ouster special meeting or the Velodyne special meeting and, for the safety of in-person attendees at the Velodyne special meeting, all bags, packages and briefcases are subject to inspection.

Additional information on attending the special meetings can be found in the section entitled “The Ouster Special Meeting” of this joint proxy statement/prospectus and in the section entitled “The Velodyne Special Meeting” of this joint proxy statement/prospectus.

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Additional information on voting procedures can be found under the section entitled “The Ouster Special Meeting” of this joint proxy statement/prospectus and under the section entitled “The Velodyne Special Meeting” of this joint proxy statement/prospectus.

If your shares of common stock in Ouster or Velodyne are held by a bank, broker or other nominee, you are considered the beneficial owner of shares held in “street name,” and your bank, broker or other nominee is considered the stockholder of record with respect to those shares. Your bank, broker or other nominee will provide you, as the beneficial owner, a package describing the procedure for voting your shares. You should follow the instructions provided by them to vote your shares. You are invited to attend the Ouster special meeting or the Velodyne special meeting, as applicable; however, you may not vote these shares in person at the Velodyne special meeting unless you obtain a signed legal proxy, executed in your favor, from your bank, broker or other nominee that holds your shares, giving you the right to vote the shares in person at the Velodyne special meeting. With respect to the Ouster special meeting, if your shares are not registered in your own name and you would like to vote your shares at the Ouster special meeting, you may visit www.virtualshareholdermeeting.com/OUST2023SM and enter the 16-digit control number included in the voting instruction card provided to you by your bank or brokerage firm. If you hold your shares in street name and you do not receive a 16-digit control number, you may need to log in to your bank or brokerage firm’s website and select the shareholder communications mailbox to access the meeting and vote. Instructions should also be provided on the voting instruction card provided by your bank or brokerage firm.

For Ouster stockholders, not instructing your bank, broker or other nominee how you wish to vote your shares will have no effect on the Ouster share issuance proposal or, assuming a quorum is present at the Ouster special meeting, the Ouster adjournment proposal. We do not expect any broker non-votes with respect to the Ouster reverse stock split proposal.

For Velodyne stockholders, not instructing your bank, broker or other nominee how you wish to vote your shares will have the same effect as a vote “AGAINST” the Velodyne merger agreement proposal, but will not

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be counted as “FOR” or “AGAINST” and, assuming a quorum is present at the Velodyne special meeting, will have no effect on, the Velodyne compensation proposal or the Velodyne adjournment proposal.

Record Holders. For shares held directly, please complete, sign, date and return each proxy card (or submit a proxy to cast your vote over the Internet, or by telephone, as provided on each proxy card) or otherwise follow the voting instructions provided in this joint proxy statement/prospectus in order to ensure that all of your shares of Ouster common stock or Velodyne common stock are voted.

Shares in “street name.” For shares held in “street name” through a bank, broker or other nominee, you should follow the procedures provided by your bank, broker or other nominee to vote your shares.

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Execution or revocation of a proxy will not in any way affect your right to attend the applicable special meeting and vote electronically at the Ouster special meeting or in person at the Velodyne special meeting, as applicable. Attending the applicable special meeting will not, by itself, revoke a proxy. Written notices of revocation and other communications with respect to the revocation of proxies should be addressed:

For more information, see the section entitled “The Ouster Special Meeting—Revocability of Proxies” of this joint proxy statement/prospectus and the section entitled “The Velodyne Special Meeting—Revocability of Proxies” of this joint proxy statement/prospectus, as applicable.

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See the section entitled “U.S. Federal Income Tax Consequences of the Mergers” of this joint proxy statement/prospectus for a more complete description of certain U.S. federal income tax consequences of the mergers. Please consult your tax advisors as to the specific tax consequences to you of the mergers.

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SELECTED UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

The following tables set forth selected unaudited pro forma condensed combined financial information giving effect to the planned mergers of Ouster and Velodyne. The unaudited pro forma condensed combined statements of operations for the nine months ended September 30, 2022 and the fiscal year ended December 31, 2021, give effect to the mergers as if they had been consummated on January 1, 2021, the beginning of Ouster’s most recently completed fiscal year. The unaudited pro forma condensed combined balance sheet as of September 30, 2022 gives effect to the mergers as if they had been consummated on September 30, 2022.

The selected unaudited pro forma condensed combined financial information is provided for illustrative purposes only and does not purport to represent what the actual consolidated results of operations or consolidated financial condition of the combined company would have been had the mergers actually occurred on the dates indicated, nor do they purport to project the future consolidated results of operations or consolidated financial condition of the combined company for any future period or as of any future date.

The selected unaudited pro forma condensed combined financial data as of and for the nine months ended September 30, 2022 and for the year ended December 31, 2021 are derived from the unaudited pro forma condensed combined financial information included under the section entitled “Unaudited Pro Forma Condensed Combined Financial Information” of this joint proxy statement/prospectus and should be read in conjunction with that information. The unaudited pro forma adjustments are based upon available information and certain assumptions that Ouster and Velodyne believe are reasonable under the circumstances. The unaudited pro forma condensed combined financial information also gives effect to the assumptions and adjustments described in the accompanying notes to the unaudited pro forma condensed combined financial statements included in this joint proxy statement/prospectus. For more information, please see the section titled “Unaudited Pro Forma Condensed Combined Financial Information” of this joint proxy statement/prospectus.

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COMPARATIVE HISTORICAL AND UNAUDITED PRO FORMA PER SHARE DATA

Presented below are Velodyne’s historical per share data for the nine months ended September 30, 2022 and the fiscal year ended December 31, 2021, Ouster’s historical per share data for the nine months ended September 30, 2022 and the fiscal year ended December 31, 2021, unaudited pro forma combined per share data for the nine months ended September 30, 2022 and the fiscal year ended December 31, 2021, and unaudited pro forma equivalent data for the nine months ended September 30, 2022 and the fiscal year ended December 31, 2021. This information should be read together with the consolidated financial statements and related notes of Velodyne and Ouster that are incorporated by reference into this joint proxy statement/prospectus and with the unaudited pro forma condensed combined financial data included under the section entitled “Unaudited Pro Forma Condensed Combined Financial Information” of this joint proxy statement/prospectus. The pro forma information is presented for illustrative purposes only and is not necessarily indicative of the operating results or financial position that would have occurred if the mergers had been completed as of the beginning of the periods presented or on the dates presented, nor is it necessarily indicative of the future operating results or financial position of the combined company. The historical book value per share is computed by dividing total stockholders’ equity by the number of shares outstanding at the end of the relevant period. The pro forma net loss per share of the combined company is computed by dividing the pro forma net loss by the pro forma weighted average number of basic and diluted shares outstanding. The pro forma book value per share of the combined company is computed by dividing total pro forma stockholders’ equity by the pro forma number of shares outstanding at the end of the period.

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COMPARISON OF OUSTER AND VELODYNE MARKET PRICES AND IMPLIED VALUE OF MERGER CONSIDERATION

The following table presents trading information for Ouster common stock on the NYSE and Velodyne common stock on the Nasdaq, respectively, on November 4, 2022, the last trading day before announcement of the mergers and November 22, 2022, the most recent practicable trading day before the date of this joint proxy statement/prospectus. The table also shows the estimated equivalent per-share value of the per share consideration proposed for each share of Velodyne common stock as of the same two dates. This estimated equivalent per-share value was calculated by multiplying the closing price of a share of Ouster common stock on the relevant date by the exchange ratio of 0.8204 shares for each share of Velodyne common stock.

The market prices of Ouster common stock and Velodyne common stock fluctuated prior to and have fluctuated after the date of the announcement of the merger agreement and may continue to fluctuate prior to the completion of the first merger. No assurance can be given concerning the market prices of Ouster common stock or Velodyne common stock before completion of the first merger or of the market price of the common stock of the combined company after completion of the first merger. Because the exchange ratio is fixed and will not be adjusted for changes in the market prices of either Ouster common stock or Velodyne common stock, the market price of Ouster common stock (and, therefore, the value of the merger consideration) when received by Velodyne stockholders after the first merger is completed could be greater than, less than or the same as shown in the table above. Accordingly, these comparisons may not provide meaningful information to Ouster stockholders and Velodyne stockholders in determining how to vote with respect to the proposals described in this joint proxy statement/prospectus. Ouster stockholders and Velodyne stockholders are encouraged to obtain current market quotations for Ouster common stock and Velodyne common stock and to review carefully the other information contained in this joint proxy statement/prospectus or incorporated by reference into this joint proxy statement/prospectus. For more information, see the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This registration statement on Form S-4, of which this joint proxy statement/prospectus forms a part, and the documents to which Ouster and Velodyne refer you to in this registration statement, as well as oral statements made or to be made by Ouster and Velodyne, include certain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks and uncertainties and are made pursuant to the safe harbor provisions of Section 27A of the Securities Act, and Section 21E of the Exchange Act. The words “believe,” “continue,” “could,” “expect,” “anticipate,” “intends,” “estimate,” “forecast,” “project,” “should,” “may,” “will,” “would” or the negative thereof and similar expressions are intended to identify such forward-looking statements. These forward-looking statements are only predictions and involve known and unknown risks and uncertainties, many of which are beyond the control of Ouster and Velodyne. Statements in or incorporated by reference into this registration statement regarding Ouster, Velodyne, or the proposed mergers, referred to as the proposed transaction, that are forward-looking, including statements regarding the anticipated benefits of the proposed transaction, the impact of the proposed transaction on Ouster’s and Velodyne’s employees, business and future financial and operating results, the amount and timing of synergies from the proposed transaction, and the closing date for the proposed transaction, are based on Ouster’s and Velodyne’s management’s estimates, assumptions and projections, and are subject to significant uncertainties and other factors, many of which are beyond Ouster’s and Velodyne’s control. These factors and risks include, but are not limited to:

In addition, material risks that could cause actual results to differ from forward-looking statements include: the inherent uncertainty associated with financial or other projections; the companies’ ability to obtain the approval of the proposed transaction by Velodyne stockholders and the approval of the Ouster share issuance proposal and the timing of the closing of the proposed transaction, including the risk that the conditions to the transaction are not satisfied on a timely basis or at all and the failure of the proposed transaction to close for any other reason; the risk that a consent or authorization that may be required for the proposed transaction is not

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obtained or is obtained subject to conditions that are not anticipated; unanticipated difficulties or expenditures relating to the proposed transaction, the response of business partners and retention as a result of the announcement and pendency of the proposed transaction; and the diversion of management time in connection with the proposed transaction.

For further discussion of these and other risks, contingencies and uncertainties applicable to Ouster and Velodyne, see the section entitled “Risk Factors” of this joint proxy statement/prospectus and in Ouster’s and Velodyne’s other filings with the SEC incorporated by reference into this joint proxy statement/prospectus. See also the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus for more information about the SEC filings incorporated by reference into this joint proxy statement/prospectus.

All subsequent written or oral forward-looking statements attributable to Ouster or Velodyne or any person acting on its or their behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section. Neither Ouster nor Velodyne is under any obligation, and each expressly disclaims any obligation, to update, alter, or otherwise revise any forward-looking statements, whether written or oral, that may be made from time to time, whether as a result of new information, future events or otherwise, except as may be required by law.

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RISK FACTORS

In deciding whether to vote for the Ouster share issuance proposal or the Ouster reverse stock split proposal, in the case of Ouster stockholders, or the adoption of the merger agreement, in the case of Velodyne stockholders, you are urged to carefully consider all of the information included or incorporated by reference in this joint proxy statement/prospectus, which is listed in the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus. You should also read and consider the risks associated with each of the businesses of Ouster and Velodyne because these risks will also affect the combined company. The risks associated with the business of Ouster can be found in Ouster’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021 and the risks associated with the business of Velodyne can be found in Velodyne’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, as such risks may be updated or supplemented in each company’s subsequently filed Quarterly Reports on Form 10-Q or Current Reports on Form 8-K (excluding any information and exhibits furnished under Item 2.02 or 7.01 thereof), each of which are incorporated by reference into this joint proxy statement/prospectus. In addition, you are urged to carefully consider the following material risks relating to the mergers, the business of the combined company, the business of Ouster, and the business of Velodyne.

Risks Relating to the Mergers

The exchange ratio is fixed and will not be adjusted in the event of any change in either Ouster’s or Velodyne’s stock price.

Upon completion of the first merger, each share of Velodyne common stock outstanding immediately prior to the first merger will be converted into and become exchangeable for 0.8204 shares of Ouster common stock. This exchange ratio is fixed in the merger agreement and will not be adjusted for changes in the market price of either Ouster common stock or Velodyne common stock. The market prices of Ouster common stock and Velodyne common stock have fluctuated prior to and after the date of the announcement of the merger agreement and may continue to fluctuate from the date of this joint proxy statement/prospectus to the date of the Ouster special meeting and the Velodyne special meeting, respectively, and the date the first merger is consummated, and the market price of the common stock of the combined company may continue to fluctuate thereafter.

Because the value of the merger consideration will depend on the market price of Ouster common stock at the time the mergers are completed, Velodyne stockholders will not know or be able to determine at the time of the Velodyne special meeting the market value of the merger consideration they would receive upon completion of the first merger. Similarly, Ouster stockholders will not know or be able to determine at the time of the Ouster special meeting the market value of the shares of Ouster common stock to be issued pursuant to the merger agreement compared to the market value of the shares of Velodyne common stock that are being exchanged in the first merger.

Stock price changes may result from a variety of factors, including, among others, general market and economic conditions, changes in Ouster’s or Velodyne’s respective businesses, operations and prospects, reductions or changes in U.S. government spending or budgetary policies, market assessments of the likelihood that the mergers will be completed, interest rates, general market, industry and economic conditions and other factors generally affecting the respective prices of Ouster’s or Velodyne’s common stock, federal, state and local legislation, governmental regulation and legal developments in the industry segments in which Ouster or Velodyne operate, and the timing of the mergers.

Many of these factors are beyond Ouster’s and Velodyne’s control, and neither Ouster nor Velodyne are permitted to terminate the merger agreement solely due to a decline in the market price of the common stock of the other party. You are urged to obtain current market quotations for Ouster common stock and Velodyne common stock in determining whether to vote for the adoption of the merger agreement, or, in the case of the Ouster stockholders, whether to vote for the Ouster share issuance proposal and the Ouster reverse stock split proposal. In addition, see the section entitled “Comparison of Ouster and Velodyne Market Prices and Implied Value of Merger Consideration” of this joint proxy statement/prospectus.

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The mergers may be delayed or may not be completed and the merger agreement may be terminated in accordance with its terms, which could negatively impact Ouster and/or Velodyne.

The mergers are subject to a number of conditions that must be satisfied, some of which are beyond the control of Ouster and Velodyne, may not be satisfied or waived in a timely manner or at all, and, accordingly, the mergers may be delayed or not completed. These conditions include: the approval by Ouster stockholders of the Ouster share issuance proposal and approval by Velodyne stockholders of the Velodyne merger agreement proposal, approval for listing on the NYSE of the shares of Ouster common stock (including those to be issued pursuant to the merger agreement) (subject to official notice of issuance), the expiration or earlier termination of any applicable waiting period under U.S. antitrust and competition laws, the absence of governmental restraints or prohibitions preventing the consummation of the mergers, the effectiveness of the registration statement on Form S-4 registering the Ouster common stock issuable pursuant to the merger agreement and the absence of any stop order by the SEC with respect thereto. The obligation of each of Ouster and Velodyne to consummate the mergers is also conditioned on, among other things, the receipt by such party of a written opinion from counsel, to the effect that for U.S. federal income tax purposes the mergers, taken together, will qualify as a “reorganization” within the meaning of Section 368(a) of the Code (discussed further below), the absence of a material adverse effect on the other party, the truth and correctness of the representations and warranties made by the other party on the date of the merger agreement and on the closing date (subject to certain materiality qualifiers), and the performance by the other party in all material respects of its obligations under the merger agreement. No assurance can be given that the required consents and approvals will be obtained or that the required conditions to closing will be satisfied, and, if all required consents and approvals are obtained and the conditions are satisfied, no assurance can be given as to the terms, conditions and timing of such consents and approvals. Any delay in completing the mergers could cause the combined company not to realize, or to be delayed in realizing, some or all of the benefits that Ouster and Velodyne expect to achieve if the mergers are successfully completed within its expected time frame. For a more complete summary of the conditions that must be satisfied or waived prior to completion of the mergers, see the section entitled “The Merger Agreement—Conditions to the Completion of the Mergers” of this joint proxy statement/prospectus.

Additionally, either Ouster or Velodyne may terminate the merger agreement under certain circumstances, including, among other reasons, if the first merger is not completed by 11:59 p.m. Pacific Time on May 4, 2023 (which date may be extended by three months under certain circumstances if certain regulatory approvals are not obtained by May 4, 2023). In addition, if the merger agreement is terminated under certain circumstances specified in the merger agreement, either party may be required to pay the other party a termination fee of $7,000,000. See the section entitled “The Merger Agreement—Termination of the Merger Agreement” of this joint proxy statement/prospectus and the section entitled “The Merger Agreement—Termination Fees” of this joint proxy statement/prospectus for a more complete discussion of the circumstances under which the merger agreement could be terminated and when a termination fee may be payable by Ouster or Velodyne.

If the mergers are not completed for any reason, including as a result of a failure to obtain the required Ouster stockholder vote to approve the Ouster share issuance proposal or the required Velodyne stockholder vote to approve the Velodyne merger agreement proposal, the ongoing businesses of Ouster and Velodyne may be adversely affected and, without realizing any of the benefits of having completed the mergers, Ouster and Velodyne would be subject to a number of risks, including the following:

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The market price for shares of common stock of the combined company following the completion of the mergers may be affected by factors different from, or in addition to, those that historically have affected or currently affect the market prices of shares of Ouster common stock and Velodyne common stock.

Upon consummation of the mergers, Ouster stockholders and Velodyne stockholders will both hold shares of common stock in the combined company. The businesses of Ouster and Velodyne differ from each other, and, accordingly, the results of operations of the combined company will be affected by some factors that are different from those currently or historically affecting the results of operations of Ouster and Velodyne. For a discussion of the businesses of each of Ouster and Velodyne and some important factors to consider in connection with those businesses, please see the section entitled “Summary—The Parties to the Mergers” of this joint proxy statement/prospectus and the documents and information included elsewhere in this joint proxy statement/prospectus or incorporated by reference into this joint proxy statement/prospectus and listed under the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus.

The shares of common stock of the combined company to be received by Velodyne stockholders as a result of the first merger will have rights different from the shares of Velodyne common stock.

Upon consummation of the first merger, the rights of Velodyne stockholders, who will become stockholders of the combined company, will be governed by the amended certificate of incorporation and bylaws of the combined company. The rights associated with Velodyne common stock are different from the rights which will be associated with the common stock of the combined company. See the section entitled “Comparison of Stockholders’ Rights” of this joint proxy statement/prospectus for a discussion of these rights.

Ouster stockholders and Velodyne stockholders will each have reduced ownership and voting interest in the combined company as compared to ownership and voting interest in each of Ouster and Velodyne on a standalone basis.

Upon consummation of the first merger, each Ouster stockholder and each Velodyne stockholder will become a stockholder of the combined company with a percentage ownership of the combined company that is smaller than such stockholder’s percentage ownership of Ouster or Velodyne, as applicable, immediately prior to the first merger. As of the date of this joint proxy statement/prospectus, based on the exchange ratio and the estimated number of shares of common stock of Ouster and Velodyne that will be outstanding immediately prior to the completion of the first merger, including exercisable options, Ouster and Velodyne estimate that holders of shares of Ouster common stock as of immediately prior to the completion of the first merger will hold, in the aggregate, approximately 50% of the issued and outstanding shares of common stock of the combined company (based on fully diluted shares outstanding of the combined company including equity awards (using the treasury stock method)) immediately following the completion of the first merger, and holders of shares of Velodyne common stock as of immediately prior to the completion of the first merger will hold, in the aggregate, approximately 50% of the issued and outstanding shares of common stock of the combined company (based on fully diluted shares outstanding of the combined company including equity awards (using the treasury stock method)) immediately following the completion of the first merger. Because of this, each share of Ouster common stock and each share of Velodyne common stock will represent a smaller percentage ownership of the combined company than it represented in Ouster or Velodyne, respectively.

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Until the completion of the mergers or the termination of the merger agreement in accordance with its terms, Ouster and Velodyne are each prohibited from entering into certain transactions and taking certain actions that might otherwise be beneficial to Ouster or Velodyne and their respective stockholders.

From and after the date of the merger agreement and prior to completion of the mergers, the merger agreement restricts Ouster and Velodyne from taking specified actions without the consent of the other party and requires that the business of each company and its respective subsidiaries be conducted in all material respects in the ordinary course of business consistent with past practice. These restrictions may prevent Ouster or Velodyne from making appropriate changes to their respective businesses or organizational structures or from pursuing attractive business opportunities that may arise prior to the completion of the mergers, and could have the effect of delaying or preventing other strategic transactions. Adverse effects arising from the pendency of the mergers could be exacerbated by any delays in consummation of the mergers or termination of the merger agreement. See the section entitled “The Merger Agreement—Conduct of Business Prior to the Effective Time” of this joint proxy statement/prospectus.

Failure to attract, motivate and retain executives and other key employees could diminish the anticipated benefits of the mergers.

The success of the mergers will depend in part on the retention of personnel critical to the business and operations of the combined company due to, for example, their technical skills or management expertise. Current and prospective employees of Ouster and Velodyne may experience uncertainty about their future role with Ouster and Velodyne until strategies with regard to these employees’ roles in the combined company are announced or executed, which may impair Ouster’s and Velodyne’s ability to attract, retain and motivate key management, sales, marketing, technical and other personnel prior to and following the mergers. If Ouster and Velodyne are unable to retain personnel, including Ouster’s and Velodyne’s key management, who are critical to the successful integration and future operations of the companies, Ouster and Velodyne could face disruptions in their respective operations, loss of existing customers or loss of sales to existing customers, loss of key information, expertise or know-how, and unanticipated additional recruitment and training costs. In addition, the loss of key personnel could diminish the anticipated benefits of the mergers.

If key employees of Ouster or Velodyne depart, the integration of the companies may be more difficult and the combined company’s business following the mergers may be harmed. Furthermore, the combined company may have to incur significant costs in identifying, hiring and retaining replacements for departing employees and may lose significant expertise and talent relating to the business of each of Ouster or Velodyne, and the combined company’s ability to realize the anticipated benefits of the mergers may be adversely affected. In addition, there could be disruptions to or distractions for the workforce and management associated with activities of labor unions or integrating employees into the combined company. No assurance can be given that the combined company will be able to attract or retain key employees of Ouster and Velodyne to the same extent that those companies have been able to attract or retain their own employees in the past.

The mergers, and uncertainty regarding the mergers, may cause customers, suppliers or strategic partners to delay or defer decisions concerning Ouster and Velodyne and adversely affect each company’s ability to effectively manage their respective businesses.

The mergers will happen only if the stated conditions are met, including the relevant stockholder approvals, among other conditions. Many of the conditions are outside the control of Ouster and Velodyne, and both parties also have certain rights to terminate the merger agreement. Accordingly, there may be uncertainty regarding the completion of the mergers. This uncertainty may cause customers, suppliers, vendors, strategic partners or others that deal with Ouster or Velodyne to delay or defer entering into contracts with Ouster or Velodyne or making other decisions concerning Ouster or Velodyne or could cause such customers, suppliers, vendors, strategic partners or others to seek to change or cancel existing business relationships with Ouster or Velodyne, which could negatively affect their respective businesses. Any delay or deferral of those decisions or changes in

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existing agreements could have an adverse impact on the respective businesses of Ouster and Velodyne, regardless of whether the mergers are ultimately completed.

Whether or not the mergers are completed, the announcement and pendency of the mergers will divert significant management resources to complete the mergers, which could have an adverse effect on Ouster’s and Velodyne’s respective businesses, financial results, and/or market prices.

Whether or not the mergers are completed, the announcement and pendency of the mergers could cause disruptions in the businesses of Ouster and Velodyne by directing the attention of management of each of Ouster and Velodyne toward the completion of the mergers. Ouster and Velodyne have each diverted significant management resources in an effort to complete the mergers and are each subject to restrictions contained in the merger agreement on the conduct of their respective businesses in the period prior to the completion of the mergers. If the mergers are not completed, Ouster and Velodyne will have incurred significant costs, including the diversion of management resources, for which they will have received little or no benefit.

The directors and executive officers of Ouster and Velodyne have interests and arrangements that may be different from, or in addition to, those of Ouster and Velodyne stockholders generally.

When considering the recommendations of the boards of directors of Ouster or Velodyne, as applicable, with respect to the proposals described in this joint proxy statement/prospectus, stockholders should be aware that the directors and executive officers of each of Ouster and Velodyne have interests in the mergers that are different from, or in addition to, those of Ouster stockholders and Velodyne stockholders generally. These interests include the continued employment of certain executive officers of Ouster and Velodyne by the combined company, the continued service of certain directors of Ouster and Velodyne as directors of the combined company, the treatment in the mergers of outstanding equity, equity-based and incentive awards, severance arrangements, and other compensation and benefit arrangements, and the right to continued indemnification of former Ouster and Velodyne directors and officers by the combined company.

Ouster stockholders and Velodyne stockholders should be aware of these interests when they consider the recommendations of the respective Ouster and Velodyne boards of directors that they vote in favor of the Ouster share issuance proposal, in the case of Ouster, or that they adopt the merger agreement, in the case of Velodyne. The interests of Ouster’s directors and executive officers are described in more detail in the section entitled “Interests of Ouster’s Directors and Executive Officers in the Mergers” of this joint proxy statement/prospectus, and the interests of Velodyne’s directors and executive officers are described in more detail in the section entitled “Interests of Velodyne’s Directors and Executive Officers in the Mergers” of this joint proxy statement/prospectus.

Ouster or Velodyne may waive one or more of the closing conditions without re-soliciting stockholder approval.

Ouster or Velodyne may determine to waive, in whole or part, one or more of the conditions to its obligations to consummate the mergers. Ouster and Velodyne currently expect to evaluate the materiality of any waiver and its effect on Ouster and Velodyne stockholders, as applicable, in light of the facts and circumstances at the time to determine whether any amendment of this joint proxy statement/prospectus or any re-solicitation of proxies or voting cards is required in light of such waiver. Any determination whether to waive any condition to the mergers or as to re-soliciting stockholder approval or amending this joint proxy statement/prospectus as a result of a waiver will be made by Ouster and Velodyne, as applicable, at the time of such waiver based on the facts and circumstances as they exist at that time.

Each of Ouster and Velodyne will incur significant transaction, merger-related and restructuring costs in connection with the mergers.

Ouster and Velodyne have each incurred and expect to incur a number of non-recurring costs associated with combining the operations of the two companies, as well as transaction fees and other costs related to the

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mergers. These costs and expenses include fees paid to financial, legal and accounting advisors, facilities and systems consolidation costs, severance and other potential employment-related costs, including retention and severance payments that may be made to certain Ouster employees and Velodyne employees, filing fees, printing expenses and other related charges. Some of these costs are payable by Ouster or Velodyne regardless of whether the mergers are completed.

The combined company may also incur restructuring and integration costs in connection with the mergers. The costs related to restructuring will be expensed as a cost of the ongoing results of operations of either Ouster or Velodyne or the combined company. There are a large number of processes, policies, procedures, operations, technologies and systems that must be integrated in connection with the mergers and the integration of the two companies’ businesses. Although Ouster and Velodyne expect that the elimination of duplicative costs, strategic benefits, additional income and the realization of other efficiencies related to the integration of the businesses may offset incremental transaction, merger-related and restructuring costs over time, any net benefit may not be achieved in the near term or at all. While both Ouster and Velodyne have assumed that certain expenses would be incurred in connection with the mergers and the other transactions contemplated by the merger agreement, there are many factors beyond their control that could affect the total amount or the timing of the integration and implementation expenses.

Ouster stockholders and Velodyne stockholders will not be entitled to appraisal rights in the mergers.

Appraisal rights are statutory rights that, if applicable under law, enable stockholders of a corporation to dissent from an extraordinary transaction, such as a merger, and to demand that such corporation pay the fair value for their shares as determined by a court in a judicial proceeding instead of receiving the consideration offered to such stockholders in connection with the transaction. Under the DGCL, stockholders do not have appraisal rights if the shares of stock they hold are either listed on a national securities exchange or held of record by more than 2,000 holders. Notwithstanding the foregoing, appraisal rights are available if stockholders are required by the terms of the merger agreement to accept for their shares anything other than (a) shares of stock of the surviving corporation, (b) shares of stock of another corporation that will either be listed on a national securities exchange or held of record by more than 2,000 holders, (c) cash in lieu of fractional shares or (d) any combination of the foregoing.

Because the mergers are of Merger Sub I with and into Velodyne and of Velodyne with and into Merger Sub II, and holders of Ouster common stock may continue to hold their shares following completion of the mergers, holders of Ouster common stock are not entitled to appraisal rights in the mergers.

Because shares of Ouster common stock are listed on the NYSE, a national securities exchange, and because Velodyne stockholders are not required by the terms of the merger agreement to accept for their shares anything other than shares of Ouster common stock and cash in lieu of fractional shares, holders of Velodyne common stock will not be entitled to appraisal rights in the mergers. See the section entitled “No Appraisal Rights” of this joint proxy statement/prospectus.

If the mergers, taken together, do not qualify as a “reorganization” under Section 368(a) of the Code, U.S. holders of Velodyne common stock may be required to pay additional U.S. federal income taxes.

For U.S. federal income tax purposes, the mergers, taken together, are intended to qualify as a “reorganization” within the meaning of Section 368(a) of the Code. It is a condition to the completion of the mergers that each of Ouster and Velodyne receive an opinion from its counsel to the effect that the mergers, taken together, will qualify as a “reorganization” within the meaning of Section 368(a) of the Code. Except where specifically discussed below, the discussion below assumes that the mergers will qualify for such tax treatment.

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Each such opinion will be based on customary assumptions and representations from Ouster and Velodyne, as well as certain warranties, covenants and undertakings by Ouster, Merger Sub I, Merger Sub II and Velodyne. If any such representations and assumptions or any other facts, representations, assumptions and exclusions set forth in such opinions is incorrect, incomplete or inaccurate, or is violated, the validity of the opinions described above may be affected and the tax consequences of the mergers could differ from those described in this joint proxy statement/prospectus.

See the section entitled “U.S. Federal Income Tax Consequences of the Mergers” of this joint proxy statement/prospectus for a more complete description of certain U.S. federal income tax consequences of the mergers. Please consult your tax advisors as to the specific tax consequences to you of the mergers.

Warrants and other shares underlying equity awards, could increase the number of shares eligible for future resale in the public market and result in dilution to the stockholders.

As of November 15, 2022, Ouster had outstanding publicly traded warrants exercisable for 15,999,900 shares of Ouster common stock at $11.50 per share, and Velodyne had (i) outstanding publicly traded warrants exercisable for 4,480,425 shares of common stock at $11.50 per share; and (ii) an outstanding private warrant owned by an affiliate of Amazon Inc., exercisable for up to 39,784,213 shares of common stock at $4.16 per share, 50% of which will vest at the effective time.

At the effective time, the Ouster Warrants will remain as the warrants exercisable for shares of Ouster common stock in accordance with the terms and conditions of the warrant agreements applicable to such Ouster Warrants. Each Velodyne Warrant will be converted into an Ouster Warrant with the same terms and conditions as applied to such Velodyne Warrant immediately prior to the effective time; however, such Ouster Warrant will cover a number of shares of Ouster common stock equal to the product of the number of shares of Velodyne common stock subject to the Velodyne Warrant and the exchange ratio and will have an exercise price per share equal to the amount obtained by dividing the per share exercise price of the Velodyne Warrant by the exchange ratio.

To the extent the trading price of Ouster common stock exceeds the applicable exercise price for the Ouster Warrants, the shares of Ouster common stock issued upon exercise of any of the Ouster Warrants will result in dilution to the then existing holders of Ouster common stock and increase the number of shares eligible for resale in the public market. Sales of substantial numbers of such shares in the public market could adversely affect the market price of the Ouster common stock.

There can be no assurance that the Ouster Warrants outstanding after the mergers will be listed on the NYSE or other national exchange.

Ouster will use its reasonable best efforts to cause the Ouster Warrants to be issued in connection with the mergers in respect of Velodyne’s publicly traded warrants to be listed on the NYSE or other national exchange. However, such listing depends in part on the Ouster Warrants meeting the applicable exchange’s listing requirements. If the Ouster Warrants are not listed on a national exchange following the mergers, there would likely be a less liquid market for those securities.

Risks Relating to the Proposed Reverse Stock Split

The proposed reverse stock split may not increase Ouster’s stock price over the long-term.

One of the Ouster stockholder proposals is the Ouster reverse stock split proposal. The mergers are not conditioned on the adoption of this stockholder proposal. One of the purposes of the contemplated reverse stock split is to increase the per share market price of Ouster common stock in order to improve the status of Ouster common stock as an investment security and help ensure that Ouster complies with the continued listing

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requirements of the NYSE. It cannot be assured, however, that the contemplated reverse stock split, if effected, will accomplish these objectives for any meaningful period of time and that Ouster common stock will not be delisted from the NYSE in the future due to a failure to satisfy the NYSE’s minimum closing bid listing standard or other NYSE listing requirements. While it is expected that the reduction in the number of outstanding shares of Ouster common stock will proportionally increase the market price of Ouster common stock, it cannot be assured that the contemplated reverse stock split, if effected, will result in any permanent or sustained increase in the market price of Ouster common stock, which is dependent upon many factors, including the combined company’s business and financial performance, general market conditions and the combined company’s prospects for future success.

Failure to obtain approval of the Ouster reverse stock split proposal may increase the probability that Ouster common stock would be delisted from the NYSE in the future due to a failure to satisfy the NYSE’s minimum closing bid listing standard.

The proposed reverse stock split may decrease the liquidity of Ouster common stock.

Although the Ouster board of directors believes that the anticipated increase in the market price of Ouster common stock could encourage interest in Ouster common stock and possibly promote greater liquidity for its stockholders, such liquidity could also be adversely affected by the reduced number of shares outstanding after the contemplated reverse stock split, if effected. The reduction in the number of outstanding shares may lead to reduced trading and a smaller number of market makers for Ouster common stock.

The proposed reverse stock split may lead to a decrease in Ouster’s overall market capitalization.

Should the market price of Ouster common stock decline after the contemplated reverse stock split, if effected, the percentage decline may be greater, due to the smaller number of shares outstanding, than it would have been prior to the contemplated reverse stock split. The contemplated reverse stock split may be viewed negatively by the market and, consequently, may lead to a decrease in Ouster’s overall market capitalization. If the per share market price does not increase in proportion to the contemplated reverse stock split ratio, then the value of Ouster, as measured by its stock market capitalization, will be reduced. In some cases, the per-share stock price of companies that have effected reverse stock splits subsequently declined back to pre-reverse split levels, and accordingly, it cannot be assured that the total market value of Ouster common stock will remain the same after the contemplated reverse stock split is effected, or that the contemplated reverse stock split will not have an adverse effect on the stock price of Ouster common stock due to the reduced number of shares outstanding after the contemplated reverse stock split.

Risks Relating to the Combined Company

Combining the businesses of Ouster and Velodyne may be more difficult, costly or time-consuming than expected, and the combined company may fail to realize the anticipated benefits of the mergers, which may adversely affect the combined company’s business results and negatively affect the value of the common stock of the combined company following the mergers.

The success of the mergers will depend on, among other things, the ability of Ouster and Velodyne to combine their businesses in a manner that realizes cost savings and facilitates growth opportunities.

Ouster and Velodyne must successfully combine their respective businesses in a manner that permits these benefits to be realized. For example, the combined company may not have sufficient capital on hand or generated from operations to continue funding operations as anticipated. In addition, the combined company must achieve the anticipated growth and cost savings without adversely affecting current revenues and investments in future growth. If the combined company is not able to successfully achieve these objectives, the anticipated benefits of the mergers may not be realized fully, or at all, or may take longer to realize than expected.

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An inability to realize the full extent of the anticipated benefits of the mergers and the other transactions contemplated by the merger agreement, as well as any delays encountered in the integration process, could have an adverse effect upon the revenues, level of expenses and operating results of the combined company, which may adversely affect the value of the common stock of the combined company after the completion of the mergers.

In addition, the actual integration may result in additional and unforeseen expenses, and the anticipated benefits of the integration plan may not be realized. Actual growth and cost savings, if achieved, may be lower than what Ouster and Velodyne expect and may take longer to achieve than anticipated. If Ouster and Velodyne are not able to adequately address integration challenges, they may be unable to realize the anticipated benefits of the integration of the two companies.

The failure to successfully integrate the businesses and operations of Ouster and Velodyne in the expected time frame may adversely affect the combined company’s future results.

Ouster and Velodyne have operated and, until the completion of the mergers, will continue to operate independently. There can be no assurances that their businesses can be integrated successfully. It is possible that the integration process could result in the loss of key Ouster employees or key Velodyne employees, the loss of customers, the disruption of either company’s or both companies’ ongoing businesses, inconsistencies in standards, controls, procedures and policies, unexpected integration issues, higher than expected integration costs and an overall post-completion integration process that takes longer than originally anticipated. Specifically, the following issues, among others, must be addressed in integrating the operations of Ouster and Velodyne in order to realize the anticipated benefits of the mergers so the combined company performs as expected:

In addition, at times the attention of certain members of either company’s or both companies’ management and resources may be focused on completion of the mergers and the integration of the businesses of the two companies and diverted from day-to-day business operations or other opportunities that may have been beneficial to such company, which may disrupt each company’s ongoing business and the business of the combined company.

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The combined company may not be able to retain customers or suppliers or customers or suppliers may seek to modify contractual obligations with the combined company, which could have an adverse effect on the combined company’s business and operations. Third parties may terminate or alter existing contracts or relationships with Ouster or Velodyne.

As a result of the mergers, the combined company may experience impacts on relationships with customers and suppliers that may harm the combined company’s business and results of operations. Certain customers, licensors, business partners or suppliers may seek to terminate or modify contractual obligations following the mergers whether or not contractual rights are triggered as a result of the mergers. There can be no guarantee that customers and suppliers will remain with or continue to have a relationship with the combined company or do so on the same or similar contractual terms following the mergers. If any customers or suppliers seek to terminate or modify contractual obligations or discontinue the relationship with the combined company, then the combined company’s business and results of operations may be harmed. Furthermore, the combined company will not have long-term arrangements with many of its significant suppliers. If the combined company’s suppliers were to seek to terminate or modify an arrangement with the combined company, then the combined company may be unable to procure necessary supplies from other suppliers in a timely and efficient manner and on acceptable terms, or at all. Any of the aforementioned disruptions could limit the combined company’s ability to achieve the anticipated benefits of the mergers. The adverse effect of any such disruptions could also be exacerbated by a delay in the completion of the mergers or by a termination of the merger agreement.

There can be no assurance that the combined company will be able to comply with the continued listing standards of the New York Stock Exchange.

If the combined company fails to satisfy the continued listing requirements of the NYSE, such as the corporate governance requirements or the minimum share price requirement, NYSE may take steps to delist the combined company’s securities. Such a delisting would likely have a negative effect on the price of the securities and would impair stockholders’ ability to sell or purchase the securities when they wish to do so. In the event of a delisting, the combined company can provide no assurance that any action taken by it to restore compliance with listing requirements would allow the securities to become listed again, stabilize the market price or improve the liquidity of the securities, prevent the securities from dropping below the NYSE minimum share price requirement or prevent future non-compliance with NYSE’s listing requirements. Additionally, if the securities are not listed on, or become delisted from the NYSE, for any reason, and are quoted on the OTC Bulletin Board, an inter-dealer automated quotation system for equity securities that is not a national securities exchange, the liquidity and price of the securities may be more limited than if the combined company were quoted or listed on the NYSE or another national securities exchange. Stockholders may be unable to sell their securities unless a market can be established or sustained.

The combined company may be exposed to increased litigation, which could have an adverse effect on the combined company’s business and operations.

The combined company may be exposed to increased litigation from stockholders, customers, suppliers, consumers and other third parties due to the combination of Ouster’s business and Velodyne’s business following the mergers. Such litigation may have an adverse impact on the combined company’s business and results of operations or may cause disruptions to the combined company’s operations.

The unaudited pro forma condensed combined financial information and certain financial forecasts included in this joint proxy statement/prospectus may not be indicative of what the combined company’s actual financial position or results of operations would have been or will be.

The unaudited pro forma condensed combined financial information included in this joint proxy statement/prospectus is presented solely for illustrative purposes and is not necessarily indicative of what the combined company’s actual financial position or results of operations would have been had the mergers been completed on

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the dates indicated. This unaudited pro forma condensed combined financial information reflects adjustments that were developed using preliminary estimates based on available information and various assumptions, and may be revised as additional information becomes available. Accordingly, the final acquisition accounting adjustments may differ materially from the pro forma adjustments reflected in this joint proxy statement/prospectus.

While presented with numeric specificity, the Ouster and Velodyne unaudited projected financial forecasts provided in this joint proxy statement/prospectus are based on numerous variables and assumptions (including, but not limited to, those related to industry performance and competition, general business, the lidar and related industries, and economic, market and financial conditions and additional matters specific to Ouster’s or Velodyne’s business, as applicable) that are inherently subjective and uncertain and are beyond the control of the respective management teams of Ouster and Velodyne. As a result, actual results may differ materially from the unaudited projected financial forecasts. Important factors that may affect actual results and cause these unaudited projected financial forecasts to not be achieved include, but are not limited to, risks and uncertainties relating to Ouster’s or Velodyne’s business, as applicable (including each company’s ability to achieve strategic goals, objectives and targets over applicable periods), industry performance, general business and economic conditions. See “The Mergers—Certain Financial Forecasts Utilized in Connection with the Mergers"

The combined company may be unable to retain Ouster and Velodyne personnel successfully after the mergers are completed.

The success of the mergers will depend in part on the combined company’s ability to retain the talents and dedication of the professionals currently employed by Ouster and Velodyne. It is possible that these employees may decide not to remain with Ouster or Velodyne, as applicable, while the mergers are pending, or with the combined company after the mergers are consummated. If key employees terminate their employment, or if an insufficient number of employees are retained to maintain effective operations, the combined company’s business activities may be adversely affected and management’s attention may be diverted from successfully integrating Ouster and Velodyne to hiring suitable replacements, all of which may cause the combined company’s business to suffer. In addition, Ouster and Velodyne may not be able to locate suitable replacements for any key employees that leave either company or to offer employment to potential replacements on reasonable terms.

Third parties may terminate or alter existing contracts or relationships with Ouster or Velodyne.

Velodyne has contracts with customers, suppliers, vendors, landlords, licensors and other business partners which may require Velodyne to obtain consent from these other parties in connection with the mergers. If these consents cannot be obtained, the combined company may suffer a loss of potential future revenue and may lose rights that are material to Velodyne’s business and the business of the combined company. In addition, third parties with whom Ouster or Velodyne currently have relationships may terminate or otherwise reduce the scope of their relationship with either party in anticipation of the mergers. Any such disruptions could limit the combined company’s ability to achieve the anticipated benefits of the mergers. The adverse effect of such disruptions could also be exacerbated by a delay in the completion of the mergers or the termination of the merger agreement.

The combined company is subject to risks arising from the ongoing COVID-19 pandemic.

The ongoing COVID-19 pandemic has impacted each of Ouster’s and Velodyne’s businesses and Ouster and Velodyne expect it to continue to impact the combined company’s business. Governments and businesses have taken, and may continue to take, unprecedented measures in response to the COVID-19 pandemic. Such measures have included restrictions on travel and business operations, temporary closures of businesses, and quarantines and shelter-in-place orders. The COVID-19 pandemic has caused significant volatility and disruption in global financial markets.

The extent to which the COVID-19 pandemic will impact the combined company is highly uncertain and is difficult to predict. The pandemic’s effects and their extent will depend on various factors, including, but not

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limited to, the duration, scope and impact of the pandemic, restrictions on business and social distancing guidelines that may be requested or mandated by governmental authorities and how quickly and to what extent normal economic and operating conditions can resume. Relevant adverse consequences of the pandemic could include reduced liquidity, increased volatility of the combined company’s stock price, operational disruption or failure due to spread of disease within the combined company or due to restrictions on business and social distancing guidelines imposed or requested by governmental authorities, unavailability of raw materials, disruption in the supply chain and increased cybersecurity and fraud risks due to increased online and remote activity, as well as the adverse consequences of a macroeconomic slowdown, recession or depression.

Even after the COVID-19 pandemic has subsided, the combined company may continue to experience adverse impacts to its business as a result of the global economic impact of the COVID-19 pandemic, including reduced availability of credit, adverse impacts on liquidity and the negative financial effects from any recession or depression that may occur.

Risks Relating to Ouster’s Business

Ouster’s business will continue to be subject to the risks described in the sections entitled “Risk Factors” in Ouster’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, in Ouster’s Quarterly Report on Form 10-Q for the quarterly periods ended June 30, 2022 and September 30, 2022, and in other documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus for the location of information incorporated by reference into this joint proxy statement/prospectus.

Risks Relating to Velodyne’s Business

Velodyne’s business will continue to be subject to the risks described in the sections entitled “Risk Factors” in Velodyne’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, in Velodyne’s Quarterly Report on Form 10-Q for the quarterly period ended September 30, 2022 and in other documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus for the location of information incorporated by reference into this joint proxy statement/prospectus.

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THE PARTIES TO THE MERGER

Ouster, Inc.

350 Treat Avenue

San Francisco, California 94110

(415) 949-0108

Ouster is a leading provider of high-resolution digital lidar sensors that offer advanced 3D vision to machinery, vehicles, robots, and fixed infrastructure assets, allowing each to understand and visualize the surrounding world and ultimately enabling safe operation and ubiquitous autonomy. Ouster’s principal executive office is located at 350 Treat Avenue, San Francisco, CA 94110. Its telephone number is (415) 949-0108.

Ouster common stock is listed on the NYSE under the ticker symbol “OUST.”

For more information about Ouster, please visit Ouster’s website at https://ouster.com/. The information contained on Ouster’s website or accessible through it (other than the documents incorporated by reference herein) does not constitute a part of this joint proxy statement/prospectus or any other report or document on file with or furnished to the SEC. Additional information about Ouster is included in the documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus.

Oban Merger Sub, Inc.

350 Treat Avenue

San Francisco, California 94110

(415) 949-0108

Oban Merger Sub, Inc., a newly formed and a direct, wholly-owned subsidiary of Ouster, is a Delaware corporation that was formed on November 1, 2022, for the sole purpose of effecting the mergers. Under the merger agreement, Oban Merger Sub, Inc. will merge with and into Velodyne as of the effective time, and Velodyne will continue as the surviving corporation and a wholly-owned subsidiary of Ouster. Oban Merger Sub, Inc. will be renamed Velodyne Lidar, Inc. following the completion of the first merger.

Oban Merger Sub II LLC

350 Treat Avenue

San Francisco, California 94110

(415) 949-0108

Oban Merger Sub II LLC, a newly formed and a direct, wholly-owned subsidiary of Ouster, is a Delaware limited liability company that was formed on November 1, 2022, for the sole purpose of effecting the mergers. Under the merger agreement, Oban Merger Sub II LLC will merge with and into Velodyne as of the effective time of the second merger, and Oban Merger Sub II LLC will continue as the surviving entity and a wholly-owned subsidiary of Ouster. Oban Merger Sub II LLC will be renamed Velodyne, LLC following the completion of the mergers.

Velodyne Lidar, Inc.

5521 Hellyer Avenue

San Jose, California 95138

(669) 275-2251

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Velodyne ushered in a new era of autonomous technology with the invention of real-time surround view lidar sensors. Velodyne’s revolutionary sensor and software solutions provide flexibility, quality and performance to meet the needs of a wide range of industries, including robotics, industrial, intelligent infrastructure, autonomous vehicles and advanced driver assistance systems (ADAS). Through continuous innovation, Velodyne strives to transform lives and communities by advancing safer mobility for all. Velodyne’s principal executive offices are located at 5521 Hellyer Avenue, San Jose, California 95138 and its telephone number is (669) 275-2251.

Velodyne common stock is listed on the Nasdaq under the ticker symbol “VLDR.”

For more information about Velodyne, please visit Velodyne’s website at https://velodynelidar.com/. The information contained on Velodyne’s website or accessible through it (other than the documents incorporated by reference herein) does not constitute a part of this joint proxy statement/prospectus or any other report or document on file with or furnished to the Securities and Exchange Commission. Additional information about Velodyne is included in the documents incorporated by reference into this joint proxy statement/prospectus. See the section entitled “Where You Can Find More Information” of this joint proxy statement/prospectus.

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THE OUSTER SPECIAL MEETING

This joint proxy statement/prospectus is being mailed on or about December 14, 2022 to holders of record of Ouster common stock as of the close of business on December 13, 2022 and constitutes notice of the Ouster special meeting in conformity with the requirements of the DGCL and the bylaws of Ouster, which are referred to as the Ouster bylaws.

This joint proxy statement/prospectus is being provided to Ouster stockholders as part of a solicitation of proxies by the Ouster board of directors for use at the Ouster special meeting and at any adjournments or postponements of the Ouster special meeting. Ouster stockholders are encouraged to read the entire document carefully, including the annexes to and documents incorporated by reference into this document, for more detailed information regarding the merger agreement and the transactions contemplated by the merger agreement.

Date, Time and Place of the Ouster Special Meeting

The Ouster special meeting is scheduled to be held completely virtually at the Ouster special meeting website, at www.virtualshareholdermeeting.com/OUST2023SM, on January 26, 2023, beginning at 9 a.m., Pacific Time, unless adjourned or postponed to a later date and/or time.

Matters to be Considered at the Ouster Special Meeting

The purposes of the Ouster special meeting are as follows, each as further described in this joint proxy statement/prospectus:

Recommendation of the Ouster Board of Directors

The Ouster board of directors unanimously recommends that Ouster stockholders vote:

After careful consideration, the Ouster board of directors (1) adopted and approved the merger agreement and the consummation of the transactions upon the terms and conditions set forth in the merger agreement, (2) determined that the terms of the merger agreement, the mergers and the other transactions are fair to, and in the best interests of, Ouster and its stockholders, (3) directed that the Ouster share issuance proposal be submitted to the stockholders of Ouster for adoption, (4) recommended that the stockholders of Ouster approve the Ouster share issuance proposal and (5) declared that the Ouster share issuance proposal is advisable.

See also the section entitled “The Mergers—Recommendation of the Ouster Board of Directors; Ouster’s Reasons for the Mergers” of this joint proxy statement/prospectus.

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Record Date for the Ouster Special Meeting and Voting Rights

The record date to determine who is entitled to receive notice of and to vote at the Ouster special meeting is December 13, 2022. As of the close of business on November 30, 2022, there were 184,952,952 shares of Ouster common stock issued and outstanding, each entitled to vote at the Ouster special meeting. Each Ouster stockholder will have one vote for any matter properly brought before the Ouster special meeting for each share of Ouster common stock such holder held at the close of business on the Ouster record date. Only Ouster stockholders of record at the close of business on the Ouster record date are entitled to receive notice of and to vote at the Ouster special meeting.

Quorum; Abstentions and Broker Non-Votes

A quorum of stockholders is necessary to conduct the Ouster special meeting. The holders of a majority in voting power of the shares of Ouster common stock issued and outstanding and entitled to vote at the meeting must be represented at the Ouster special meeting electronically or by proxy in order to constitute a quorum. Abstentions will be counted for purposes of determining whether a quorum exists. If a quorum is not present, the Ouster special meeting will be adjourned until the holders of the number of shares of Ouster common stock required to constitute a quorum attend, whether electronically or by proxy.

Under NYSE rules, banks, brokers or other nominees who hold shares in “street name” for a beneficial owner of those shares typically have the authority to vote in their discretion on “routine” proposals when they have not received instructions from beneficial owners. However, banks, brokers or other nominees are not allowed to exercise their voting discretion with respect to the approval of matters that NYSE determines to be “non-routine.” Generally, a broker non-vote occurs on an item when (a) a bank, broker or other nominee has discretionary authority to vote on one or more “routine” proposals to be voted on at a meeting of stockholders, but is not permitted to vote on other “non-routine” proposals without instructions from the beneficial owner of the shares and (b) the beneficial owner fails to provide the bank, broker or other nominee with such instructions. Under NYSE rules, “non-routine” matters include the Ouster share issuance proposal (Ouster Proposal #1) and the Ouster adjournment proposal (Ouster Proposal #3). With respect to the Ouster share issuance proposal (Ouster Proposal #1) and the Ouster adjournment proposal (Ouster Proposal #3), if you hold your shares of Ouster common stock in “street name,” your shares will not be voted on any matter unless you affirmatively instruct your bank, broker or other nominee how to vote your shares in one of the ways indicated by your bank, broker or other nominee. It is therefore critical that you cast your vote by instructing your bank, broker or other nominee on how to vote. The NYSE rules governing brokers’ discretionary authority will not permit brokers to exercise discretionary authority regarding the Ouster share issuance proposal or the Ouster adjournment proposal, to be voted on at the Ouster special meeting. These NYSE rules are applicable to the votes to be held at the Ouster special meeting since Ouster common stock is currently listed on the NYSE.

Under NYSE rules, the Ouster reverse stock split proposal (Ouster Proposal #2) is a routine matter for which brokers are expected to have discretionary authority to vote. Ouster does not expect any broker non-votes in connection with Ouster Proposal #2.

If you submit a properly executed proxy card, even if you abstain from voting or vote against the adoption of the Ouster share issuance proposal, the Ouster reverse stock split proposal or the Ouster adjournment proposal, your shares of Ouster common stock will be counted for purposes of calculating whether a quorum is present at the Ouster special meeting. Executed but unvoted proxies will be voted in accordance with the recommendations of the Ouster board of directors. If additional votes must be solicited to adopt the Ouster share issuance proposal and the Ouster reverse stock split proposal, it is expected that the meeting will be adjourned to solicit additional proxies.

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As of November 30, 2022, Ouster directors and executive officers, and their affiliates, as a group, owned and were entitled to vote 24,156,632 shares of Ouster common stock, or approximately 12.31% of the total outstanding shares of Ouster common stock as of such date. The directors and executive officers of Ouster, and their affiliates, have entered into voting and support agreements obligating them to vote their shares “FOR” the Ouster share issuance proposal, “FOR” the Ouster reverse stock split proposal and “FOR” the Ouster adjournment proposal. See also the section entitled “Interests of Ouster’s Directors and Executive Officers in the Mergers” of this joint proxy statement/prospectus and the arrangements described in Part III of Ouster’s Annual Report on Form 10-K for the fiscal year ended on December 31, 2021, as well as the information specifically incorporated by reference in Part III of Ouster’s Annual Report on Form 10-K for the fiscal year ended on December 31, 2021, from Ouster’s Definitive Proxy Statement on Schedule 14A for Ouster’s 2022 annual meeting filed with the SEC on April 27, 2022, which information is incorporated into this joint proxy statement/prospectus by reference.

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Methods of Voting

If you are a stockholder of record as of the record date for the Ouster special meeting, you may vote by proxy through the Internet, by telephone, or by mail, or by voting electronically at the Ouster special meeting. For shares held through a bank, broker or other nominee in “street name” instead of as a registered holder, you may vote by submitting your voting instructions to your bank, broker or other nominee. In most instances, you will be able to do this over the Internet, by telephone or by mail as indicated below. Please refer to the information from your bank, broker or other nominee on how to submit voting instructions. If you do not provide voting instructions to your bank, broker or other nominee, your shares of Ouster common stock will not be voted on the Ouster share issuance proposal or the Ouster adjournment proposal as your bank, broker or other nominee does not have discretionary authority to vote on such proposals at the Ouster special meeting; see the section entitled “—Quorum; Abstentions and Broker Non-Votes” of this joint proxy statement/prospectus.

If you are a stockholder of record, proxies submitted over the Internet, by telephone or by mail as described above should be received by 11:59 p.m., Eastern Time, on January 25, 2023. To reduce administrative costs and help the environment by conserving natural resources, Ouster asks that you submit a proxy to vote through the Internet, which is available 24 hours a day.

Notwithstanding the above, if your shares are held in “street name” by a bank, broker or other nominee, you should follow the instructions you receive from your bank, broker or other nominee on how to vote your shares. Registered stockholders who attend the Ouster special meeting may vote their shares electronically even if they previously have voted their shares.

If you deliver a proxy pursuant to this joint proxy statement/prospectus, but do not specify a choice with respect to any proposal set forth in this joint proxy statement/prospectus, your underlying shares of Ouster common stock will be voted on such uninstructed proposal in accordance with the recommendation of the Ouster board of directors. No matters other than the proposals listed above will be brought before the Ouster special meeting and the Ouster bylaws provide that the only business that may be conducted at the Ouster special meeting are those proposals brought before the meeting pursuant to this joint proxy statement/prospectus.

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Revocability of Proxies

Any stockholder giving a proxy has the right to revoke it before the proxy is voted at the Ouster special meeting by:

Execution or revocation of a proxy will not in any way affect the stockholder’s right to attend the special meeting and vote electronically.

Written notices of revocation and other communications with respect to the revocation of proxies should be addressed to:

Ouster, Inc.

Attn: Corporate Secretary

350 Treat Ave

San Francisco, CA 94110

If your shares are held in “street name” and you previously provided voting instructions to your broker, bank or other nominee, you should follow the instructions provided by your broker, bank or other nominee to revoke or change your voting instructions.

Proxy Solicitation Costs

Ouster is soliciting proxies to provide an opportunity to all Ouster stockholders to vote on agenda items, whether or not the stockholders are able to attend the Ouster special meeting or an adjournment or postponement thereof. Ouster will bear the entire cost of soliciting proxies from its stockholders, except that Ouster and Velodyne have agreed to each pay one half of the costs and expenses of filing, printing and mailing this joint proxy statement/prospectus and all filing and other similar fees payable to the SEC in connection with this joint proxy statement/prospectus. In addition to the solicitation of proxies by mail, Ouster will ask banks, brokers and other custodians, nominees and fiduciaries to forward the proxy solicitation materials to the beneficial owners of shares of Ouster common stock held of record by such nominee holders. Ouster may be required to reimburse these nominee holders for their customary clerical and mailing expenses incurred in forwarding the proxy solicitation materials to the beneficial owners.

Ouster has retained MacKenzie Partners, Inc., referred to as MacKenzie Partners, to assist in the solicitation process. Ouster estimates that it will pay MacKenzie Partners a fee of approximately $10,000, plus reimbursement of reasonable expenses. Ouster also has agreed to indemnify MacKenzie Partners against various liabilities and expenses that relate to or arise out of its solicitation of proxies (subject to certain exceptions). Proxies may be solicited on behalf of Ouster or by Ouster directors, officers and other employees in person, by mail, by telephone, by facsimile, by messenger, via the Internet or by other means of communication, including electronic communication. Directors, officers and employees of Ouster will not be paid any additional amounts for their services or solicitation in this regard.

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Attending the Ouster Special Meeting

You are entitled to attend the Ouster special meeting only if you are a stockholder of record of Ouster at the close of business on December 13, 2022 (the record date for the Ouster special meeting) or you hold your shares of Ouster beneficially in the name of a broker, bank or other nominee as of the Ouster record date, or you hold a valid proxy for the Ouster special meeting.

To participate in the Ouster special meeting, you will need the 16-digit control number included on your proxy card or on the instructions that accompanied your proxy materials. The meeting webcast will begin promptly at 9 a.m., Pacific Time. We encourage you to access the meeting prior to the start time. Online check-in will begin at 8:45 a.m., Pacific Time, and you should allow ample time for check-in procedures. If you hold your shares through a bank or broker, instructions should also be provided on the voting instruction card provided by your bank or brokerage firm. If you lose your 16-digit control number, you may join the Ouster special meeting as a “Guest,” but you will not be able to vote, ask questions, or access the list of stockholders as of the record date.

If you plan to attend the Ouster special meeting and vote electronically, Ouster still encourages you to submit a proxy to vote in advance by the Internet, by telephone or (if you received a paper copy of the proxy materials) by mail so that your vote will be counted even if you later decide not to attend the Ouster special meeting. Submitting your proxy by the Internet, by telephone or by mail will not limit your right to vote at the Ouster special meeting if you later decide to attend electronically.

Householding

The SEC’s rules permit us to deliver a single set of proxy materials to one address shared by two or more of our stockholders. This delivery method is referred to as “householding” and can result in significant cost savings. To take advantage of this opportunity, we have delivered only one set of proxy materials to multiple stockholders who share an address, unless we received contrary instructions from the impacted stockholders prior to the mailing date. We agree to deliver promptly, upon written or oral request, a separate set of proxy materials, as requested, to any stockholder at the shared address to which a single set of those documents was delivered. If you prefer to receive separate copies of the proxy materials, contact MacKenzie Partners, Inc. at (800) 322-2885 or in writing at MacKenzie Partners, Inc., Householding Department, 1407 Broadway, 27^th Floor, New York, New York 10018.

If you are currently a stockholder sharing an address with another stockholder and wish to receive only one set of future proxy materials for your household, please contact MacKenzie Partners, Inc. at the above phone number or address.

Tabulation of Votes

The Ouster board of directors will appoint an independent inspector of election for the Ouster special meeting. The inspector of election will, among other matters, determine the number of shares of Ouster common stock represented electronically or by proxy at the Ouster special meeting to confirm the existence of a quorum, determine the validity of all proxies and ballots and certify the results of voting on all proposals submitted to Ouster stockholders.

Adjournments

If a quorum is present at the Ouster special meeting but there are not sufficient votes at the time of the Ouster special meeting to approve the Ouster share issuance proposal, or, if additional time is necessary to ensure that any supplement or amendment to the accompanying joint proxy statement/prospectus is timely provided to Ouster stockholders, then Ouster stockholders may be asked to vote on the Ouster adjournment proposal.

At any subsequent reconvening of the Ouster special meeting at which a quorum is present, any business may be transacted that might have been transacted at the original meeting and all proxies will be voted in the

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same manner as they would have been voted at the original convening of the Ouster special meeting, except for any proxies that have been effectively revoked or withdrawn prior to the time the proxy is voted at the reconvened meeting.

Assistance

If you need assistance voting or in completing your proxy card or have questions regarding the Ouster special meeting or the mergers, please contact MacKenzie Partners, Inc., the proxy solicitation agent for Ouster:

MacKenzie Partners, Inc.

1407 Broadway, 27th Floor

New York, New York 10018

(212) 929 5500 (Call Collect)

Call Toll Free: (800) 322 2885

proxy@mackenziepartners.com

OUSTER STOCKHOLDERS SHOULD CAREFULLY READ THIS JOINT PROXY STATEMENT/PROSPECTUS IN ITS ENTIRETY FOR MORE DETAILED INFORMATION CONCERNING THE MERGER AGREEMENT AND THE MERGERS. IN PARTICULAR, OUSTER STOCKHOLDERS ARE DIRECTED TO THE MERGER AGREEMENT, WHICH IS ATTACHED AS ANNEX A HERETO.

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