SUPPLEMENTAL DISCLOSURES TO DEFINITIVE PROXY STATEMENT
This supplemental information should be read in conjunction with the Definitive Proxy Statement, which should be read in its entirety.
Achillion believes that no further disclosure is required to supplement the Definitive Proxy Statement under applicable laws; however to avoid the risk that lawsuits may delay or otherwise adversely affect the consummation of the proposed Merger and
to minimize the expense of defending such action, Achillion wishes to voluntarily make supplemental disclosures related to the proposed Merger, which are set forth below, in response to certain allegations. Nothing in these supplemental disclosures
shall be deemed an admission of the legal necessity or materiality under applicable laws of any of the disclosures set forth herein. Defined terms used but not defined herein have the meanings set forth in the Definitive Proxy Statement.
Supplemental disclosure is indicated by underlines and strikethroughs as appropriate.
Each of the disclosure under the section
entitled Summary Legal Proceedings Regarding the Merger and the section entitled The Merger Legal Proceedings Regarding the Merger is hereby supplemented by replacing each of the paragraph entitled
Stockholder Litigation with the paragraph immediately below, which amends each paragraph entitled Stockholder Litigation on page 9 and page 73, respectively, by stating there are eight (8) stockholder actions filed and
adding the underlined language:
Beginning on November 6, 2019, eight (8) purported Achillion stockholders filed actions
in federal courts in Delaware, Pennsylvania, and New York, captioned Wang v. Achillion Pharmaceuticals, Inc., et al., Case No.
1:19-cv-02104-RGA (D. Del.), Rosenblatt v. Achillion Pharmaceuticals, Inc., et al., Case No. 1:19-cv-02112-RGA (D. Del.), Orende v. Achillion Pharmaceuticals, Inc., et al., Case No. 2:19-cv-05281-MAK (E.D. Pa.), Petit-Frere v. Achillion Pharmaceuticals Inc., et al., Case No. 1:19-cv-10602-JMF (S.D.N.Y.), Hand v. Achillion Pharmaceuticals, Inc., et al., Case No. 1:19-cv-06456-CBA-ST (E.D.N.Y.), Atto v. Achillion Pharmaceuticals, Inc., et al., Case No. 1:19-cv-10807-JMF (S.D.N.Y.), Greene v. Achillion Pharmaceuticals, Inc., et al.,
Case No. 1:19-cv-10945-UA (S.D.N.Y.), and Petrella v. Achillion Pharmaceuticals, Inc., et al., Case No. 1:19-cv-10974-UA (S.D.N.Y.), alleging claims related to the Merger. The complaints name as defendants Achillion and the Board of Directors. The complaints allege, among
other things, claims under Sections 14(a) and 20(a) of the Exchange Act asserting that the preliminary proxy statement filed by Achillion in connection with the Merger is materially incomplete and misleading, and the Orende complaint also alleges
claims for breach of fiduciary duties in connection with the Merger. The Rosenblatt and Orende actions seek to allege claims on behalf of a putative class of stockholders of Achillion. The complaints seek to enjoin the Merger (or, in the
alternative, to rescind the Merger or receive an award of recessionary damages in the event the Merger is completed), a declaration that the defendants violated Sections 14(a) and 20(a) of the Exchange Act and Rule
14a-9 promulgated thereunder, and an award of costs and attorneys and expert fees. The defendants believe these complaints are without merit.
The disclosure under the section entitled The Merger Background of the Merger is hereby supplemented by adding the
following underlined language to the eleventh paragraph on page 37:
On June 27, 2019, the Board of Directors held a meeting,
which included members of senior management, and representatives of Centerview and Skadden. During the meeting, members of senior management discussed with the Board of Directors the financial projections prepared by management, the implied
valuation of the June 21 Proposal and the discussions with Alexion leading to such proposal, and Centerview shared preliminary illustrative financial analyses of Achillion. For more information on these projections, see the section of this
proxy statement captioned Certain Financial Projections, beginning on page 54 of this proxy statement.
The
disclosure under the section entitled The Merger Background of the Merger is hereby supplemented by adding the following underlined language to the sixth paragraph on page 40:
On September 26 and 27, 2019, the Board of Directors held a regularly-scheduled two-day in-person meeting in New York, New York, where the Board of Directors discussed the potential entry into a strategic transaction with Alexion or Company A, and various matters in the ordinary course of
Achillions business. Skadden attended the meeting session regarding a potential transaction via teleconference while Centerview attended in person. The Board of Directors discussed the most recent developments with respect to Achillions
product candidates and the expected timeline for certain developments. Mr. Gibney reported on his latest discussions with Dr. Sarin, his guidance to her to improve the Alexion offer, and her response. Management discussed with the Board
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