Amylyx Pharmaceuticals ownership update: Perceptive Life Sciences Master Fund, Ltd. directly holds 8,284,882 shares of Common Stock, representing 7.5% of the class based on 111,186,317 shares outstanding as of April 27, 2026. Perceptive Advisors LLC is the investment manager and Joseph Edelman is the managing member; all three Reporting Persons report shared voting and dispositive power over the same 8,284,882 shares.
Positive
None.
Negative
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Insights
Perceptive group reports a significant passive stake of 7.5%
The filing shows the Master Fund directly holds 8,284,882 shares, equal to 7.5% of outstanding Common Stock as of April 27, 2026. Ownership is reported as shared voting and dispositive power via the investment manager structure.
Cash‑flow treatment and any planned transactions are not disclosed in the excerpt; subsequent filings would provide changes in position or sales.
Key Figures
Shares held by Master Fund:8,284,882 sharesPercent of class:7.5%Shares outstanding:111,186,317 shares
3 metrics
Shares held by Master Fund8,284,882 sharesDirect holdings reported for Perceptive Life Sciences Master Fund
Percent of class7.5%Ownership percentage based on shares outstanding as of April 27, 2026
Shares outstanding111,186,317 sharesOutstanding Common Stock used to compute ownership percentage as of April 27, 2026
"The Master Fund directly holds 8,284,882 shares of Common Stock."
Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.
shared dispositive powerregulatory
"Shared Dispositive Power 8,284,882.00 reported for each Reporting Person"
Schedule 13G/Aregulatory
"The names of the persons filing this report (collectively, the "Reporting Persons") with respect to shares"
A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 4)
Amylyx Pharmaceuticals, Inc.
(Name of Issuer)
Common Stock, $0.0001 par value per share
(Title of Class of Securities)
03237H101
(CUSIP Number)
03/31/2026
(Date of Event Which Requires Filing of this Statement)
Check the appropriate box to designate the rule pursuant to which this Schedule is filed:
Rule 13d-1(b)
Rule 13d-1(c)
Rule 13d-1(d)
schemaVersion:
SCHEDULE 13G
CUSIP Number(s):
03237H101
1
Names of Reporting Persons
Perceptive Advisors LLC
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
DELAWARE
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
8,284,882.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
8,284,882.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
8,284,882.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
7.5 %
12
Type of Reporting Person (See Instructions)
IA
SCHEDULE 13G
CUSIP Number(s):
03237H101
1
Names of Reporting Persons
Joseph Edelman
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
UNITED STATES
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
8,284,882.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
8,284,882.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
8,284,882.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
7.5 %
12
Type of Reporting Person (See Instructions)
IN
SCHEDULE 13G
CUSIP Number(s):
03237H101
1
Names of Reporting Persons
Perceptive Life Sciences Master Fund, Ltd.
2
Check the appropriate box if a member of a Group (see instructions)
(a)
(b)
3
Sec Use Only
4
Citizenship or Place of Organization
CAYMAN ISLANDS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
8,284,882.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
8,284,882.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
8,284,882.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
11
Percent of class represented by amount in row (9)
7.5 %
12
Type of Reporting Person (See Instructions)
CO
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Amylyx Pharmaceuticals, Inc.
(b)
Address of issuer's principal executive offices:
55 Cambridge Parkway, Suite 6W, Cambridge, Massachusetts 02142
Item 2.
(a)
Name of person filing:
The names of the persons filing this report (collectively, the "Reporting Persons") with respect to shares of Common Stock, par value $0.0001 per share (the "Common Stock") of Amylyx Pharmaceuticals, Inc. (the "Issuer") are:
(i) Perceptive Advisors LLC ("Perceptive Advisors")
(ii) Joseph Edelman ("Mr. Edelman")
(iii) Perceptive Life Sciences Master Fund, Ltd. (the "Master Fund")
(b)
Address or principal business office or, if none, residence:
The address of the principal business office of each of the Reporting Persons is:
51 Astor Place, 10th Floor, New York, NY 10003
(c)
Citizenship:
Perceptive Advisors is a Delaware limited liability company.
Mr. Edelman is a United States citizen.
The Master Fund is a Cayman Islands corporation.
(d)
Title of class of securities:
Common Stock, $0.0001 par value per share
(e)
CUSIP No.:
03237H101
Item 3.
If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)
Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)
Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)
Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)
Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)
An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)
An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)
A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)
A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)
A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)
A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
(k)
Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.
Ownership
(a)
Amount beneficially owned:
The information required by this item with respect to each Reporting Person is set forth in Rows 5 through 9 of the cover pages to this Schedule 13G. The ownership percentages reported are based on 111,186,317 shares of Common Stock outstanding as of April 27, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 7, 2026.
The Master Fund directly holds 8,284,882 shares of Common Stock. Perceptive Advisors serves as the investment manager to the Master Fund. Mr. Edelman is the managing member of Perceptive Advisors.
(b)
Percent of class:
Perceptive Advisors: 7.5%
Mr. Edelman: 7.5%
Master Fund: 7.5%
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
Perceptive Advisors: 0
Mr. Edelman: 0
Master Fund: 0
(ii) Shared power to vote or to direct the vote:
Perceptive Advisors: 8,284,882
Mr. Edelman: 8,284,882
Master Fund: 8,284,882
(iii) Sole power to dispose or to direct the disposition of:
Perceptive Advisors: 0
Mr. Edelman: 0
Master Fund: 0
(iv) Shared power to dispose or to direct the disposition of:
Perceptive Advisors: 8,284,882
Mr. Edelman: 8,284,882
Master Fund: 8,284,882
Item 5.
Ownership of 5 Percent or Less of a Class.
Not Applicable
Item 6.
Ownership of more than 5 Percent on Behalf of Another Person.
Not Applicable
Item 7.
Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
Not Applicable
Item 8.
Identification and Classification of Members of the Group.
Not Applicable
Item 9.
Notice of Dissolution of Group.
Not Applicable
Item 10.
Certifications:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under ?? 240.14a-11.
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.
What stake does Perceptive Life Sciences Master Fund hold in AMLX?
The Master Fund directly holds 8,284,882 shares, representing 7.5% of Common Stock based on 111,186,317 shares outstanding as of April 27, 2026. The filing attributes shared voting and dispositive power to the Reporting Persons.
Who are the Reporting Persons on the Schedule 13G/A for AMLX?
The Reporting Persons are Perceptive Advisors LLC, Joseph Edelman, and Perceptive Life Sciences Master Fund, Ltd.. Perceptive Advisors is the investment manager and Mr. Edelman is the managing member, at the address shown in the filing.
How is voting and dispositive power reported for the 8,284,882 shares?
Each Reporting Person reports 0 sole voting power and 8,284,882 shared voting power, and likewise 0 sole dispositive power with 8,284,882 shared dispositive power, per the cover page rows in the filing.
What outstanding share count does the filing use to calculate percentage ownership?
The filing uses 111,186,317 shares outstanding as of April 27, 2026, taken from the Issuer's Form 10-Q referenced in the Schedule 13G/A, to compute the 7.5% ownership percentages.
Does the Schedule 13G/A disclose any planned sales or purchases by Perceptive?
The excerpt reports current beneficial ownership and control relationships only. It does not disclose any planned purchases, sales, or cash‑flow treatment for the reported 8,284,882 shares.
