Baker Bros. Advisors LP and related entities filed a Schedule 13G reporting beneficial ownership of 10,012,267 Alkermes plc ordinary shares, equal to 6.1% of the class, based on 165,117,509 shares outstanding as of October 24, 2025.
The shares are held through two investment funds: 667, L.P. with 845,828 shares (0.5%) and Baker Brothers Life Sciences, L.P. with 9,166,439 shares (5.6%). The filing states the securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control of Alkermes.
Positive
None.
Negative
None.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
Alkermes plc.
(Name of Issuer)
Ordinary Shares, $0.01 per share
(Title of Class of Securities)
G01767105
(CUSIP Number)
12/31/2025
(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)
SCHEDULE 13G
CUSIP No.
G01767105
1
Names of Reporting Persons
Baker Bros. Advisors LP
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
10,012,267.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
10,012,267.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
10,012,267.00
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)
6.1 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP No.
G01767105
1
Names of Reporting Persons
Baker Bros. Advisors (GP) 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
10,012,267.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
10,012,267.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
10,012,267.00
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)
6.1 %
12
Type of Reporting Person (See Instructions)
HC, OO
SCHEDULE 13G
CUSIP No.
G01767105
1
Names of Reporting Persons
Julian C. Baker
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
10,012,267.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
10,012,267.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
10,012,267.00
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)
6.1 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
CUSIP No.
G01767105
1
Names of Reporting Persons
Felix J. Baker
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
10,012,267.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
10,012,267.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
10,012,267.00
10
Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)
This Schedule 13G is being filed jointly by Baker Bros. Advisors LP (the "Adviser"), Baker Bros. Advisors (GP) LLC (the "Adviser GP"), Julian C. Baker and Felix J. Baker (collectively, the "Reporting Persons").
(b)
Address or principal business office or, if none, residence:
The business address of each of the Reporting Persons is:
c/o Baker Bros. Advisors LP
860 Washington Street, 3rd Floor
New York, NY 10014
(212) 339-5690
(c)
Citizenship:
The Adviser is a limited partnership organized under the laws of the State of Delaware. The Adviser GP is a limited liability company organized under the laws of the State of Delaware. The citizenship of each of Julian C. Baker and Felix J. Baker is the United States of America.
(d)
Title of class of securities:
Ordinary Shares, $0.01 per share
(e)
CUSIP No.:
G01767105
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:
Items 5 through 9 and 11 of each of the cover pages to this Schedule 13G are incorporated herein by reference. Set forth below is the aggregate number of ordinary shares ("Common Stock") of Alkermes plc. (the "Issuer") directly held by each of Baker Brothers Life Sciences, L.P. ("Life Sciences") and 667, L.P. ("667", and together with Life Sciences, the "Funds") which may be deemed to be indirectly beneficially owned by the Reporting Persons.
The percentage of beneficial ownership for each of the Reporting Persons reported herein and the information set forth below is based on 165,117,509 shares of Common Stock outstanding as of October 24, 2025, as reported in the Issuer's Form 10-Q filed with the Securities and Exchanges Commission ("SEC") on October 28, 2025. Such percentage figures are calculated in accordance with Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the "Exchange Act").
Pursuant to the management agreements, as amended, among the Adviser, the Funds and their respective general partners, the Funds' respective general partners relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds, and thus the Adviser has complete and unlimited discretion and authority with respect to the Funds' investments and voting power over investments.
The Adviser GP is the sole general partner of the Adviser. The Adviser GP, Felix J. Baker and Julian C. Baker as managing members of the Adviser GP, and the Adviser may be deemed to be beneficial owners of securities of the Issuer directly held by the Funds.
(b)
Percent of class:
The Funds beneficially own 10,012,267 shares of Common Stock or 6.1% of the outstanding Common Stock. 667 beneficially owns 0.5% and Life Sciences beneficially owns 5.6% of the outstanding Common Stock.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
667 directly holds 845,828 shares of Common Stock and Life Sciences directly holds 9,166,439 shares of Common Stock.
(ii) Shared power to vote or to direct the vote:
0
(iii) Sole power to dispose or to direct the disposition of:
667 directly holds 845,828 shares of Common Stock and Life Sciences directly holds 9,166,439 shares of Common Stock.
(iv) Shared power to dispose or to direct the disposition of:
0
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.
If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary.
The information in Item 4 is incorporated herein by reference.
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 acquired and are held in the ordinary course of business and 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.
Baker Bros. Advisors LP
Signature:
/s/ Scott L. Lessing
Name/Title:
Scott L. Lessing/ President By: Baker Bros. Advisors (GP) LLC, its general partner
