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Sirenia Capital Management LP and Alex Silverstein report beneficial ownership of AnaptysBio, Inc. common stock on a Schedule 13G/A. They collectively report holding 1,491,959 shares of common stock, representing 5.0% of the class, based on 29,608,481 shares outstanding as of June 22, 2026.
The shares are held in a managed account of Point72 Associates II, LLC (the Sirenia Account), for which Sirenia and Mr. Silverstein report shared voting and dispositive power over all 1,491,959 shares and no sole voting or dispositive power. The filers state that the ownership is reported without conceding beneficial ownership status under Section 13.
Key Figures
Shares beneficially owned:1,491,959 sharesPercent of class:5.0%Shares outstanding baseline:29,608,481 shares+2 more
5 metrics
Shares beneficially owned1,491,959 sharesCommon stock of AnaptysBio reported by Sirenia Capital Management and Alex Silverstein
Percent of class5.0%Portion of AnaptysBio common stock beneficially owned by the reporting persons
Shares outstanding baseline29,608,481 sharesAnaptysBio common stock outstanding as of June 22, 2026, per Definitive Proxy Statement
Shared voting power1,491,959 sharesShares over which the reporting persons have shared power to vote or direct the vote
Shared dispositive power1,491,959 sharesShares over which the reporting persons have shared power to dispose or direct disposition
"the beneficial owner of the securities reported herein"
A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.
shared voting powerregulatory
"Shared Voting Power 1,491,959.00"
Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.
shared dispositive powerregulatory
"Shared Dispositive Power 1,491,959.00"
Schedule 13Gregulatory
"Ownership of more than 5 Percent on Behalf of Another Person."
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.
percent of classfinancial
"Percent of class: 5.0%"
Percent of class is the portion of a specific category of securities—such as a company’s common shares, preferred shares, or a bond series—that takes part in or approves a corporate action (vote, consent, tender, etc.). Investors watch this number because it reveals how much support or opposition exists within that particular shareholder group; like counting how many members of a club back a proposal, it can determine whether a plan passes or how influence is distributed.
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What percentage of AnaptysBio (ANAB) shares does Sirenia Capital Management report owning?
Sirenia Capital Management and Alex Silverstein report beneficial ownership of 5.0% of AnaptysBio’s common stock. This is based on 1,491,959 shares out of 29,608,481 shares outstanding as of June 22, 2026.
How many AnaptysBio (ANAB) shares are reported as beneficially owned in this Schedule 13G/A?
The reporting persons disclose beneficial ownership of 1,491,959 shares of AnaptysBio common stock. This position is held in a managed account (the Sirenia Account) and represents 5.0% of the outstanding common shares.
Who are the reporting persons on this AnaptysBio (ANAB) Schedule 13G/A amendment?
The reporting persons are Sirenia Capital Management LP and Alex Silverstein. Sirenia manages the Sirenia Account, and Silverstein is the managing member of Sirenia Capital Management GP LLC, the general partner of Sirenia.
What voting power do the reporting persons have over AnaptysBio (ANAB) shares?
The reporting persons disclose 0 shares with sole voting power and 1,491,959 shares with shared voting power. They likewise report shared dispositive power over all 1,491,959 AnaptysBio shares held in the Sirenia Account.
Which account actually holds the AnaptysBio (ANAB) shares reported by Sirenia Capital Management?
The shares are held in the Sirenia Account, an account of Point72 Associates II, LLC. That account has the right to receive dividends or sale proceeds from more than 5% of AnaptysBio’s outstanding common stock.
On what share count is the 5.0% AnaptysBio (ANAB) ownership calculation based?
The reported 5.0% ownership is calculated using 29,608,481 shares of AnaptysBio common stock outstanding as of June 22, 2026, as stated in the company’s Definitive Proxy Statement on Schedule 14A.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 1)
ANAPTYSBIO, INC
(Name of Issuer)
Common Stock, par value $0.001 per share
(Title of Class of Securities)
032724106
(CUSIP Number)
06/30/2026
(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
1,491,959.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,491,959.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,491,959.00
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)
5.0 %
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
1,491,959.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
1,491,959.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,491,959.00
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)
5.0 %
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 a managed account it manages (the "Sirenia Account"); 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 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.
(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 No.:
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 29,608,481 shares of Common Stock outstanding as of June 22, 2026, as reported in the Issuer's Definitive Proxy Statement on Schedule 14A filed with the Securities and Exchange Commission on June 29, 2026.
(b)
Percent of class:
5.0%
(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). The Sirenia Account, which is an account of Point72 Associates II, LLC, has the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, more than 5 percent of the outstanding Common Stock.
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.
See Item 2(a) and Item 3.
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
