Item 4 — Purpose of Transaction
On March 31, 2026, Biogen, Aspen Purchaser Sub, Inc. ("Purchaser"), a Delaware corporation and a wholly owned subsidiary of Biogen, and Apellis, entered into an Agreement and Plan of Merger (the "Merger Agreement"). Pursuant to the Merger Agreement, and upon the terms and subject to the conditions therein, Purchaser will commence a tender offer (the "Offer") to acquire any and all outstanding shares of common stock, par value $0.0001 per share, of Apellis (the "Apellis Common Stock"), in exchange for (i) $41.00 per share of Apellis Common Stock, net to the seller in cash, without interest and subject to reduction for any applicable tax withholding (such amount, or any higher amount per share paid pursuant to the Offer, the "Upfront Consideration"), plus (ii) one contractual, non-transferable contingent value right per share of Apellis Common Stock (each, a "CVR"), which shall entitle the holder to receive potential payments of up to an aggregate of $4.00 in cash, without interest and subject to reduction for any applicable tax withholding, upon the achievement of certain specified milestones described below in accordance with the terms and conditions of a contingent value rights agreement (the "CVR Agreement") included as Exhibit B to the Merger Agreement, to be entered into with a rights agent (the "Rights Agent") mutually acceptable to Biogen and Apellis (the Upfront Consideration plus one CVR, together, the "Offer Price"). The Offer will remain open for 20 business days, subject to extension under certain circumstances. Promptly following the consummation of the Offer, subject to the terms and conditions set forth in the Merger Agreement, Purchaser will merge with and into Apellis, with Apellis continuing as the surviving corporation and a wholly owned subsidiary of Biogen (the "Merger"). The Merger Agreement contemplates that the Merger will be effected pursuant to Section 251(h) of the General Corporation Law of the State of Delaware (the "DGCL"), with no stockholder vote required to consummate the Merger. At the effective time of the Merger (the "Effective Time"), each share of Apellis Common Stock (other than shares of Apellis Common Stock that are (i) held in the treasury of Apellis, (ii) irrevocably accepted for purchase in the Offer by Purchaser and "received" (as such term is defined by Section 251(h)(6)(f) of the DGCL) by Purchaser, (iii) held by Biogen, Purchaser or any other wholly owned subsidiary of Biogen as of both the commencement of the Offer and immediately prior to the Effective Time and (iv) held by stockholders who are entitled to, and properly demand, appraisal for such shares of Apellis Common Stock in accordance with Section 262 of the DGCL) will be cancelled and converted into the right to receive the Offer Price without interest, subject to reduction for any applicable withholding taxes (the "Merger Consideration"). On March 31, 2026, concurrently with the execution of the Merger Agreement, Biogen and Purchaser entered into a tender and support agreement (the "Tender and Support Agreement") with certain of Apellis' current directors and executive officers, Cedric Francois, Gerald Chan, Alec Machiels and Pascal Deschatelets, and Morningside Venture Investments, Ltd., a stockholder of Apellis (collectively, the "Support Stockholders"), solely in their respective capacities as stockholders of Apellis, pursuant to which each Support Stockholder agreed, among other things, (i) to tender all of the shares of Apellis Common Stock held by such Support Stockholder in the Offer, (ii) to, if applicable, vote all of such Support Stockholder's shares of Apellis Common Stock in favor of the Merger and (iii) to certain other restrictions on its ability to take actions with respect to Apellis and its shares of Apellis Common Stock. At or prior to the time at which Purchaser irrevocably accepts for purchase all shares of Apellis Common Stock validly tendered (and not validly withdrawn) pursuant to the Offer, Biogen, Apellis and the Rights Agent will enter into the CVR Agreement. Each CVR represents a non-transferable contractual contingent right to receive the following cash payments, without interest and subject to reduction for any applicable tax withholding (the "Milestone Payments") if the following milestones (the "Milestones") are achieved: $2.00 per CVR, upon the achievement of Annual Net Sales, as defined in the CVR Agreement, of at least $1,500,000,000 attributable to SYFOVRE(R) and related products in the aggregate during the 2027, 2028, 2029 or 2030 calendar years (the "Net Sales Milestone 1"); or $2.00 per CVR, upon the achievement of Annual Net Sales, as defined in the CVR Agreement, of at least $2,000,000,000 attributable to SYFOVRE(R) and related products in the aggregate during the 2027, 2028, 2029, 2030 or 2031 calendar years (the "Net Sales Milestone 2"), provided that if the Net Sales Milestone 1 is not met prior to December 31, 2030 but the Net Sales Milestone 2 is achieved d