BLUE bluebird bio Inc

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14D-9

(Amendment No. 4)

Solicitation/Recommendation Statement

Under Section 14(d)(4) of the Securities Exchange Act of 1934

bluebird bio, Inc.

(Name of Subject Company)

bluebird bio, Inc.

(Name of Person Filing Statement)

Common Stock, par value $0.01 per share

(Title of Class of Securities)

09609G 209

(CUSIP Number of Class of Securities)

Andrew Obenshain

President and Chief Executive Officer

bluebird bio, Inc.

455 Grand Union Boulevard

Somerville, Massachusetts 02145

(339) 499-9300

(Name, address and telephone number of person authorized to receive notices and communications

on behalf of the persons filing statement)

With copies to:

R. Scott Shean

Andrew Clark

Brian R. Umanoff

Latham & Watkins LLP

650 Town Center Drive, 20th Floor

Costa Mesa, CA 92626

(714) 540-1235

This Amendment No. 4 (this “Amendment”) amends and supplements the Solicitation/Recommendation Statement on Schedule 14D-9 (as amended or supplemented from time to time, the “Schedule 14D-9”) filed by bluebird bio, Inc., a Delaware corporation (“bluebird” or the “Company”), with the U.S. Securities and Exchange Commission (the “SEC”) on March 7, 2025, relating to the tender offer by Beacon Merger Sub, Inc., a Delaware corporation (“Merger Sub”) and an indirect wholly owned subsidiary of Beacon Parent Holdings, L.P., a Delaware limited partnership (“Parent”), to purchase all of the outstanding Shares in exchange for (i) $3.00 in cash per Share, subject to any applicable withholding taxes and without interest thereon (the “Closing Amount”), plus (ii) one contingent value right (each, a “CVR”) per Share, representing the right to receive one contingent payment of $6.84 in cash, subject to any applicable withholding taxes and without interest thereon, payable upon the achievement of the milestone specified in, and subject to and in accordance with the terms and conditions set forth in, the Contingent Value Rights Agreement (the “CVR Agreement”) (the Closing Amount plus one CVR, collectively, or any greater amount per Share that may be paid pursuant to the Offer (as defined below), the “Offer Price”), on the terms and subject to the conditions set forth in the Offer to Purchase, dated March 7, 2025 (as it may be amended, supplemented or otherwise modified from time to time, the “Offer to Purchase”), and in the related Letter of Transmittal (which, together with the Offer to Purchase, as each may be amended, supplemented or otherwise modified from time to time, constitute the “Offer”). The Offer is described in a Tender Offer Statement on Schedule TO (as amended or supplemented from time to time, the “Schedule TO”) filed by Parent and Merger Sub with the U.S. Securities and Exchange Commission (the “SEC”) on March 7, 2025, as amended. The Offer to Purchase and Letter of Transmittal are filed as Exhibits (a)(1)(A) and (a)(1)(B), respectively, to the Schedule TO and are incorporated herein by reference.

Except to the extent specifically provided in this Amendment, the information set forth in the Schedule 14D-9 remains unchanged. Capitalized terms used, but not otherwise defined, in this Amendment shall have the meanings ascribed to them in the Schedule 14D-9. This Amendment is being filed to reflect certain updates as reflected below.

Item 9. Exhibits.

Item 9 of the Schedule 14D-9 is hereby amended and supplemented by inserting the following exhibits thereto:

SIGNATURE

After due inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Exhibit (a)(5)(L)

From: DocuSign via tender@bluebirdbio.com

To: MorganStanley distribution list

Subject: Action from bluebird bio: Complete tender election form

Hello,

You are receiving this notification because our records indicate that you currently hold shares of bluebird bio, Inc. (“bluebird”) stock in a Shareworks account. All stockholders of bluebird are receiving instructions on how to tender the shares they hold into the tender offer (the “Tender Offer”) in connection with the acquisition agreement announced on February 21, 2025 between bluebird and funds managed by global investment firms Carlyle and SK Capital.

As a reminder:

Tendering is discretionary, and tendered shares may be withdrawn at any time prior to the expiration of the Tender Offer. If you do not complete this form, the shares you hold in Shareworks will not be tendered into the Tender Offer. Additional instructions are below. Email tender@bluebirdbio.com prior to the expiration of the Tender Offer if you wish to withdraw your tender.

Please reach out to tender@bluebirdbio.com with any questions.

Joe Vittiglio

Chief Legal Officer

bluebird bio

How to tender shares:

Additional Information and Where to Find It

This communication is not an offer to buy nor a solicitation of an offer to sell any securities of bluebird. The solicitation and the offer to buy shares of bluebird’s common stock is being made pursuant to a Tender Offer Statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials, that were filed by Parent and Merger Sub with the SEC on March 7, 2025. In addition, bluebird has filed a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer with the SEC on March 7, 2025. The tender offer materials and the Solicitation/Recommendation statement, as they may be amended from time to time, contain important information that should be read carefully when they become available and considered before any decision is made with respect to the tender offer. Investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and bluebird with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, copies of these materials and other documents by calling Innisfree M&A Incorporated, the information agent for the Offer, toll-free at (877) 825-8793 for stockholders or by calling collect at (212) 750-5833 for banks or brokers.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9 OF BLUEBIRD AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

Exhibit (a)(5)(M)

Election Form to Tender Shares of Common Stock

of

BLUEBIRD BIO, INC.

at $3.00 in cash per share, plus one contingent value right per share representing the right to receive a contingent payment of $6.84 in cash upon the achievement of a specified milestone pursuant to the Offer to Purchase, dated March 7, 2025, by BEACON MERGER SUB, INC., a wholly-owned subsidiary of BEACON MIDCO, INC., a wholly-owned subsidiary of BEACON PARENT HOLDINGS, L.P., whose general partner is BEACON GENERAL PARTNER, LLC, an affiliate of CARLYLE PARTNERS GROWTH, L.P., SK CAPITAL PARTNERS VI-A, L.P. and SK CAPITAL PARTNERS VI-B, L.P.

You have received this Election Form in connection with the offer (the “Offer”) by Beacon Merger Sub, Inc. (“Merger Sub”), a Delaware corporation and an indirect wholly owned subsidiary of Beacon Parent Holdings, L.P. (“Parent”), a Delaware limited partnership, to purchase all of the outstanding shares of common stock, par value $0.01 per share (the “Shares”), of bluebird bio, Inc., a Delaware corporation (“bluebird”), in exchange for (i) $3.00 in cash per Share on the terms and subject to the conditions set forth in the Offer to Purchase, dated March 7, 2025 (as it may be amended, supplemented or otherwise modified from time to time, the “Offer to Purchase”) plus (ii) one contingent value right (each, a “CVR”) per Share, subject to and in accordance with the terms and conditions set forth in the Contingent Value Rights Agreement that will be entered into by and among Parent, a rights agent mutually agreeable to Parent and bluebird, and, solely for certain purposes, the Surviving Corporation (as defined in the Offer to Purchase) (the “CVR Agreement”), representing the right to receive one contingent payment of $6.84 in cash, subject to any applicable withholding taxes and without interest thereon, payable upon the achievement of the specified milestone set forth in, and subject to the terms and conditions of the CVR Agreement and the Offer to Purchase.

Our records indicate that you currently hold Shares in your Shareworks Stock Plan Account. Please confirm your name in the space below, and indicate how many of your Shares you wish to tender in the Offer.

Please complete this form no later than 3:00 p.m. Eastern Time on April 17, 2025.

You cannot tender more Shares than you currently hold in your Shareworks Stock Plan Account. If you indicate that you wish to tender a greater number of Shares than you currently hold in your Shareworks Stock Plan Account, you will be deemed to have elected to tender all of the Shares you currently hold.

Additional Information and Where to Find It

This communication is not an offer to buy nor a solicitation of an offer to sell any securities of bluebird. The solicitation and the offer to buy shares of bluebird’s common stock is being made pursuant to a Tender Offer Statement on Schedule TO, including an offer to purchase, a letter of transmittal and other related materials, that were filed by Parent and Merger Sub with the SEC on March 7, 2025. In addition, bluebird has filed a Solicitation/Recommendation Statement on Schedule 14D-9 with respect to the tender offer with the SEC on March 7, 2025. The tender offer materials and the Solicitation/Recommendation statement, as they may be amended from time to time, contain important information that should be read carefully when they become available and considered before any decision is made with respect to the tender offer. Investors will be able to obtain a free copy of these materials and other documents filed by Parent, Merger Sub and bluebird with the SEC at the website maintained by the SEC at www.sec.gov. Investors may also obtain, at no charge, copies of these materials and other documents by calling Innisfree M&A Incorporated, the information agent for the Offer, toll-free at (877) 825-8793 for stockholders or by calling collect at (212) 750-5833 for banks or brokers.

INVESTORS AND SECURITY HOLDERS ARE ADVISED TO READ THESE DOCUMENTS, INCLUDING THE SOLICITATION/RECOMMENDATION STATEMENT ON SCHEDULE 14D-9 OF BLUEBIRD AND ANY AMENDMENTS THERETO, AS WELL AS ANY OTHER DOCUMENTS RELATING TO THE TENDER OFFER AND THE MERGER THAT ARE FILED WITH THE SEC, CAREFULLY AND IN THEIR ENTIRETY PRIOR TO MAKING ANY DECISIONS WITH RESPECT TO WHETHER TO TENDER THEIR SHARES INTO THE TENDER OFFER BECAUSE THEY CONTAIN IMPORTANT INFORMATION, INCLUDING THE TERMS AND CONDITIONS OF THE TENDER OFFER.

[Signature Page Follows]

Acknowledged and agreed:

(Signature Page to Tender Election Form)