# EDGAR Filing Document

**Accession Number:** 0001597553
**File Stem:** 0000950157-25-000586
**Filing Date:** 2025-7
**Character Count:** 11219
**Document Hash:** 3f1310f0c847e1a393db8253749ae74e
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000950157-25-000586.hdr.sgml**: 20250721

**ACCESSION NUMBER**: 0000950157-25-000586

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

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250721

**DATE AS OF CHANGE**: 20250721

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Sage Therapeutics, Inc.
- **CENTRAL INDEX KEY:** 0001597553
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-88275
- **FILM NUMBER:** 251138464

**BUSINESS ADDRESS:**
- **STREET 1:** 55 CAMBRIDGE PARKWAY
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-299-8380

**MAIL ADDRESS:**
- **STREET 1:** 55 CAMBRIDGE PARKWAY
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
**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:** 7814642000

**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)**

**Sage Therapeutics, Inc.**

*(Name of Issuer)*

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

*(Title of Class of Securities)*

**78667J108**

*(CUSIP Number)*

**Wendell Taylor, Secretary**<br>Biogen Inc.<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)*

**07/21/2025**

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

| **CUSIP No.** | **78667J108** |

---

| | | | |
|:--|:--|:--|:--|
| 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>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (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>**6241473.00** |
| 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>**6241473.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**6241473.00** | Aggregate amount beneficially owned by each reporting person<br>**6241473.00** | |
| 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>**10%** | Percent of class represented by amount in Row (11)<br>**10%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

**Comment for Reporting Person:** With respect to Row 13 above, the calculation is based on the number of shares of Common Stock of the Issuer outstanding as of April 22, 2025, as disclosed in the Issuer's most recent quarterly report on Form 10-Q filed on April 29, 2025.

| **CUSIP No.** | **78667J108** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Biogen MA Inc.** | Name of reporting person<br>**Biogen MA Inc.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[x] (a)<br>[ ] (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>**MASSACHUSETTS** | Citizenship or place of organization<br>**MASSACHUSETTS** | |
| 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>**6241473.00** |
| 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>**6241473.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**6241473.00** | Aggregate amount beneficially owned by each reporting person<br>**6241473.00** | |
| 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>**10%** | Percent of class represented by amount in Row (11)<br>**10%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**CO** | Type of Reporting Person (See Instructions)<br>**CO** | |

---

**Comment for Reporting Person:** With respect to Row 13 above, the calculation is based on the number of shares of Common Stock of the Issuer outstanding as of April 22, 2025, as disclosed in the Issuer's most recent quarterly report on Form 10-Q filed on April 29, 2025.

**Item 1. Security and Issuer**

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

**(b) Name of Issuer:**
Sage Therapeutics, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
55 Cambridge Parkway, Cambridge, MA, 02142

This Amendment No. 1 to Schedule 13D (this "Amendment") amends and supplements the previously filed statement on Schedule 13D filed on January 10, 2025 (as amended and supplemented from time to time, the "Schedule 13D").

Except as set forth below, all Items of the Schedule 13D remain unchanged. Capitalized terms used in this Amendment and not otherwise defined shall have the respective meanings assigned to such terms in the Schedule 13D. The information set forth in response to each separate Item below shall be deemed to be a response to all Items where such information is relevant. The Schedule 13D is hereby supplementally amended as follows:

**Item 4. Purpose of Transaction**

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

From March 2025 through May 2025, the Reporting Persons engaged in discussions and diligence with the Issuer with respect to a potential sale of the Issuer to the Reporting Persons. On May 5, 2025, the Reporting Persons submitted to representatives of the Issuer a non-binding proposal to acquire all of the outstanding shares of Common Stock not owned by the Reporting Persons or their subsidiaries for an upfront payment of $9.00 per share in cash and one contingent value right per share representing the right to receive $2.00 in cash upon annual net sales of ZURZUVAE in the U.S. in a calendar year first equaling or exceeding $450 million and $2.00 in cash upon annual net sales of ZURZUVAE in the U.S. in a calendar year first equaling or exceeding $700 million (the "May 5 Proposal"). The May 5 Proposal was submitted subject to resolution of specific diligence matters. After the May 5 Proposal, representatives of the Reporting Persons and representatives of the Issuer continued to engage in discussions and diligence with respect to a potential transaction (including with respect to such specific diligence matters). On May 15, 2025, the Issuer terminated all discussions and diligence with respect to a potential transaction with the Reporting Persons.

On June 16, 2025, the Issuer announced that it entered into an Agreement and Plan of Merger (the "Merger Agreement"), dated June 13, 2025, with Supernus Pharmaceuticals, Inc., a Delaware corporation ("Parent"), and Saphire, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Purchaser"), pursuant to which, upon the terms and subject to the conditions therein, Purchaser will commence a tender offer (the "Offer") to acquire all of the Issuer's issued and outstanding Common Stock in exchange for $8.50 per share in cash plus one contingent value right per share representing the right to receive up to $3.50 per share upon the satisfaction of certain milestones. On July 2, 2025, Purchaser commenced the Offer, which Offer is currently scheduled to expire at one minute following 11:59 P.M., Eastern Time, on July 30, 2025, unless extended or earlier terminated (the "Offer Expiration Time").

At or before the Offer Expiration Time, the Reporting Persons intend to tender all or a portion of the Common Stock held by the Reporting Persons to Purchaser in the Offer or to dispose of all or a portion of the Common Stock held by the Reporting Persons.

The Reporting Persons do not intend to disclose developments with respect to the foregoing, except as required by applicable law.

### 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/ Michael Dambach

**Name/Title:** Michael Dambach / Treasurer

**Date:** 07/21/2025

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 MA Inc.

**Signature:** /s/ Michael Dambach

**Name/Title:** Michael Dambach / Treasurer

**Date:** 07/21/2025