# EDGAR Filing Document

**Accession Number:** 0001492422
**File Stem:** 0000950157-26-000611
**Filing Date:** 2026-5
**Character Count:** 8424
**Document Hash:** 4f19fd37257f94cca0245c845de90e9f
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000950157-26-000611.hdr.sgml**: 20260514

**ACCESSION NUMBER**: 0000950157-26-000611

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260514

**DATE AS OF CHANGE**: 20260514

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Apellis Pharmaceuticals, Inc.
- **CENTRAL INDEX KEY:** 0001492422
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 271537290
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-90187
- **FILM NUMBER:** 26979736

**BUSINESS ADDRESS:**
- **STREET 1:** 100 FIFTH AVENUE
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
- **BUSINESS PHONE:** 617-977-5700

**MAIL ADDRESS:**
- **STREET 1:** 100 FIFTH AVENUE
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** BIOGEN INC.
- **CENTRAL INDEX KEY:** 0000875045
- **STANDARD INDUSTRIAL CLASSIFICATION:** BIOLOGICAL PRODUCTS (NO DIAGNOSTIC SUBSTANCES) [2836]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 330112644
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**BUSINESS ADDRESS:**
- **STREET 1:** 225 BINNEY STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 6176792000

**MAIL ADDRESS:**
- **STREET 1:** 225 BINNEY STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** BIOGEN IDEC INC.
- **DATE OF NAME CHANGE:** 20070427

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** BIOGEN IDEC INC
- **DATE OF NAME CHANGE:** 20031112

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** IDEC PHARMACEUTICALS CORP / DE
- **DATE OF NAME CHANGE:** 19970530

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**(Amendment No. 1)**

**Apellis Pharmaceuticals, Inc.**

*(Name of Issuer)*

**Common Stock, par value $0.0001 per share**

*(Title of Class of Securities)*

**—**

*(CUSIP Number)*

**Wendell Taylor, Secretary**<br>225 Binney Street<br>Cambridge MA 02142<br>(617) 679-2000

*(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)*

**05/14/2026**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Biogen Inc.** | Name of reporting person<br>**Biogen Inc.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**OO** | Source of funds (See Instructions)<br>**OO** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**0.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**0.00** | Aggregate amount beneficially owned by each reporting person<br>**0.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0.0%** | Percent of class represented by amount in Row (11)<br>**0.0%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

**Comment for Reporting Person:** This Amendment No. 1 to Schedule 13D (this "Amendment") relates to the common stock, par value $0.0001 per share (the "Shares"), of Apellis Pharmaceuticals, Inc., a Delaware corporation ("Apellis") and amends and supplements the statement on Schedule 13D originally filed by Biogen Inc., a Delaware corporation ("Biogen"), on April 6, 2026 (the "Prior Schedule 13D"). The filing of this Amendment represents the final amendment to the Prior Schedule 13D and constitutes an exit filing for the Reporting Person.

Except as otherwise specified in this Amendment, all items left blank remain unchanged in all material respects and any items that are reported are deemed to amend and restate the corresponding items in the Prior Schedule 13D. Unless otherwise indicated, all capitalized terms used herein but not defined herein shall have the same meanings ascribed to them in the Prior Schedule 13D.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock, par value $0.0001 per share

**(b) Name of Issuer:**
Apellis Pharmaceuticals, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
100 Fifth Avenue, Waltham, MA, 02451

**Item 4. Purpose of Transaction**

Item 4 of the Prior Schedule 13D is hereby amended and supplemented by adding the following at the end thereof:

As previously disclosed, on March 31, 2026, Biogen entered into an Agreement and Plan of Merger (the "Merger Agreement") with Apellis and Aspen Purchaser Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Biogen ("Purchaser"). Pursuant to the Merger Agreement, on April 14, 2026, Purchaser commenced a tender offer (the "Offer") to acquire any and all outstanding Shares, in exchange for (i) $41.00 per Share, net to the seller in cash, without interest and subject to reduction for any applicable tax withholding (the "Cash Amount"), plus (ii) one contractual, non-transferable contingent value right per Share (each, a "CVR") representing the right to receive contingent cash 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, in each case upon the terms and subject to the conditions set forth in the Offer to Purchase, dated April 14, 2026 (as amended or supplemented from time to time, the "Offer to Purchase") and in the related Letter of Transmittal.

As a result of the satisfaction of the Minimum Condition (as defined in the Offer) and each of the other conditions to the Offer, on May 14, 2026, Purchaser irrevocably accepted for payment all Shares that were validly tendered (and not validly withdrawn) pursuant to the Offer. Following the completion of the Offer, on May 14, 2026, pursuant to the terms of the Merger Agreement, Purchaser merged with and into Apellis, without a vote of the stockholders of Apellis in accordance with Section 251(h) of the General Corporation Law of the State of Delaware, with Apellis continuing as the surviving corporation of the merger and as a wholly owned subsidiary of Biogen (the "Merger").

**Item 5. Interest in Securities of the Issuer**

**(a)**
Items 5(a), (b) and (e) of the Prior Schedule 13D are hereby amended and supplemented by adding the following at the end thereof:

On May 14, 2026, the Merger was consummated and Purchaser was merged with and into Apellis, with Apellis surviving the Merger as a wholly owned subsidiary of Biogen. Upon the consummation of the Merger, the Tender and Support Agreement automatically terminated pursuant to its terms and is of no further force or effect.

**(b)**
—

**(c)**
—

### SIGNATURE

After reasonable 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.

**Reporting Person:** Biogen Inc.

**Signature:** /s/ Wendell Taylor

**Name/Title:** Wendell Taylor / Secretary

**Date:** 05/14/2026