AnaptysBio, Inc. Schedule 13G disclosure states that Sirenia Capital Management and Alex Silverstein report shared dispositive power over 1,920,402 shares of AnaptysBio common stock, representing 6.7% of the class. The filing bases the percentage on 28,748,255 shares outstanding as of February 27, 2026. The report covers holdings by the Sirenia Fund and Sirenia Account; a Joint Filing Agreement is included as Exhibit 99.1.
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Insights
Sirenia reports a 6.7% beneficial stake via shared dispositive power.
Sirenia Capital Management and Alex Silverstein disclose shared voting and dispositive power over 1,920,402 shares, calculated against 28,748,255 shares outstanding as of February 27, 2026. The filing is a routine Schedule 13G disclosure for an investor exceeding 5%.
Cash‑flow treatment and any planned transactions are not stated in the excerpt; subsequent filings would show changes in holdings or voting intentions.
Filing follows Rule 13d-1(k) joint filing practice with Exhibit 99.1 included.
The statement identifies Sirenia and Mr. Silverstein as Reporting Persons, provides addresses and citizenship, and incorporates a Joint Filing Agreement (Exhibit 99.1). The percentage was computed using the issuer's Form 10-K share count for the period referenced.
Signatures by Kolby Loft and Alex Silverstein finalize the schedule; no additional qualifiers or contingent actions are shown in the provided text.
Key Figures
Shares beneficially owned:1,920,402 sharesPercent of class:6.7%Shares outstanding:28,748,255 shares
3 metrics
Shares beneficially owned1,920,402 sharesheld by Sirenia Fund and Sirenia Account
Percent of class6.7%percentage of class based on outstanding shares as of Feb 27, 2026
Shares outstanding28,748,255 sharesoutstanding as of <date>February 27, 2026</date> (Form 10-K)
"This statement is filed by: (i) Sirenia Capital Management LP"
A Schedule 13G is a formal document that investors file with the government when they acquire a large ownership stake in a company, usually for investment purposes rather than control. It helps keep the public informed about who owns significant parts of a company's shares, which can influence how the company is managed and how investors make decisions. Filing this schedule is important for transparency and understanding the ownership landscape of publicly traded companies.
shared dispositive powerregulatory
"Shared Dispositive Power 1,920,402.00"
beneficially ownedfinancial
"Amount beneficially owned: The information required by Item 4(a)"
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.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
AnaptysBio, Inc.
(Name of Issuer)
Common Stock, par value $0.001 per share
(Title of Class of Securities)
032724106
(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):
032724106
1
Names of Reporting Persons
Sirenia Capital Management 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
0.00
6
Shared Voting Power
1,920,402.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,920,402.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,920,402.00
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)
6.7 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP Number(s):
032724106
1
Names of Reporting Persons
Alex Silverstein
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
1,920,402.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,920,402.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,920,402.00
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)
6.7 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
AnaptysBio, Inc.
(b)
Address of issuer's principal executive offices:
10770 Wateridge Circle, Suite 210, San Diego, CA 92121
Item 2.
(a)
Name of person filing:
This statement is filed by:
(i) Sirenia Capital Management LP ("Sirenia") with respect to the common stock, par value $0.001 per share ("Common Stock"), of AnaptysBio, Inc. (the "Issuer") held by an investment fund (the "Sirenia Fund") and managed account (the "Sirenia Account") it manages; and
(ii) Alex Silverstein ("Mr. Silverstein"), the managing member of Sirenia Capital Management GP LLC, the general partner of Sirenia, with respect to the Common Stock held by the Sirenia Fund and Sirenia Account.
The foregoing persons are hereinafter sometimes collectively referred to as the "Reporting Persons."
The filing of this statement should not be construed as an admission that any of the foregoing persons or any Reporting Person is, for the purposes of Section 13 of the Securities Exchange Act of 1934, the beneficial owner of the securities reported herein.
Sirenia and Mr. Silverstein have entered into a Joint Filing Agreement, a copy of which is filed with this Schedule 13G as Exhibit 99.1, pursuant to which they have agreed to file this Schedule 13G jointly in accordance with the provisions of Rule 13d-1(k) of the Securities Exchange Act of 1934 (the "Act").
(b)
Address or principal business office or, if none, residence:
The address of the principal business office of Sirenia and Mr. Silverstein is 1674 Meridian Avenue, Suite 320, Miami Beach, FL 33139.
(c)
Citizenship:
Sirenia is a Delaware limited partnership. Mr. Silverstein is a United States citizen.
(d)
Title of class of securities:
Common Stock, par value $0.001 per share
(e)
CUSIP Number(s):
032724106
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 Item 4(a) is set forth in Row 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
The percentage set forth in this Schedule 13G is calculated based upon an aggregate of 28,748,255 shares of Common Stock outstanding as of February 27, 2026, as reported in the Issuer's Annual Report on Form 10-K for the fiscal year ended December 31, 2025, filed with the Securities and Exchange Commission on March 3, 2026.
(b)
Percent of class:
6.7%
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
The information required by Item 4(c)(i) is set forth in Row 5 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
(ii) Shared power to vote or to direct the vote:
The information required by Item 4(c)(ii) is set forth in Row 6 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
(iii) Sole power to dispose or to direct the disposition of:
The information required by Item 4(c)(iii) is set forth in Row 7 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
(iv) Shared power to dispose or to direct the disposition of:
The information required by Item 4(c)(iv) is set forth in Row 8 of the cover page for each of the Reporting Persons and is incorporated herein by reference.
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.
If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required.
See Item 2(a).
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 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.
Sirenia Capital Management LP
Signature:
/s/ Kolby Loft
Name/Title:
Kolby Loft, General Counsel & Chief Compliance Officer
What stake does Sirenia Capital report in AnaptysBio (ANAB)?
Sirenia reports shared dispositive control over 1,920,402 shares, equal to 6.7% of the class, based on 28,748,255 shares outstanding as of February 27, 2026. The holdings are held via the Sirenia Fund and Sirenia Account.
Who is filing the Schedule 13G for ANAB?
The Schedule 13G is filed jointly by Sirenia Capital Management LP and Alex Silverstein, the managing member of Sirenia's general partner. A Joint Filing Agreement is attached as Exhibit 99.1 to the filing.
Does the filing state how many shares AnaptysBio had outstanding?
Yes, the filing uses the issuer's reported total of 28,748,255 shares outstanding as of February 27, 2026 from the company's Annual Report on Form 10-K for the year ended December 31, 2025.
Are voting and dispositive powers held solely by Sirenia or shared?
The filing shows 0 sole voting and 0 sole dispositive power and reports 1,920,402 shared voting and 1,920,402 shared dispositive power for the Reporting Persons, indicating shared control over the reported shares.
Does the Schedule 13G disclose planned sales or purchases by Sirenia?
No transaction plans are disclosed in the provided excerpt. The filing reports current beneficial ownership and includes signature pages; it does not state any intended purchases or sales of AnaptysBio shares.
