[SCHEDULE 13G/A] SUTRO BIOPHARMA, INC. Amended Passive Investment Disclosure
Affinity Asset Advisors reports 6.5% stake in Sutro
Affinity Asset Advisors and Michael Cho report ownership of 1,069,519 shares of Sutro Biopharma common stock, representing approximately 6.5% of the outstanding common stock as of March 31, 2026.
Affinity Asset Advisors and Michael Cho report ownership of 1,069,519 shares of Sutro Biopharma common stock, representing approximately 6.5% of the outstanding common stock as of March 31, 2026.
The filing states the percentage is calculated using 16,567,762 shares outstanding as of March 31, 2026, per the issuer's Definitive Proxy Statement filed April 22, 2026. The Reporting Persons hold sole voting and sole dispositive power over the reported shares.
Positive
None.
Negative
None.
Insights
Affinity Asset Advisors reports a significant passive stake in Sutro Biopharma.
The amendment shows the Adviser and Michael Cho beneficially own 1,069,519 shares, equal to 6.5% of Sutro Biopharma as of March 31, 2026, calculated on an outstanding base of 16,567,762 shares. The filing attributes sole voting and dispositive power to the Reporting Persons.
The position size is material for governance monitoring; subsequent filings or Schedule 13D would be required if activist intentions or changes in control arise. Future disclosures in company filings may specify any changes to the stake or voting intentions.
Key Figures
Filing type:SCHEDULE 13G/AShares beneficially owned:1,069,519 sharesPercent of class:6.5%+1 more
Shares beneficially owned1,069,519 sharesAs of March 31, 2026
Percent of class6.5%Based on 16,567,762 shares outstanding as of March 31, 2026
Shares outstanding (base)16,567,762 sharesAs of March 31, 2026 per Definitive Proxy Statement filed April 22, 2026
Key Terms
beneficially own, sole dispositive power, Schedule 13G/A
3 terms
beneficially ownregulatory
"As of March 31, 2026, the Adviser and Mr. Cho beneficially own 1,069,519 shares"
Beneficially own means having the economic rights and risks of a security—such as the right to receive dividends, sell the shares, or profit from price changes—whether or not your name appears on the official share register. Think of it like renting a car: you use it and reap the benefits even if the title lists someone else. Investors care because beneficial ownership determines who truly controls value, must be disclosed under securities rules, and can signal potential influence or trading activity that affects a stock’s price.
sole dispositive powerregulatory
"the Reporting Persons have sole power to dispose or to direct the disposition of 1,069,519 shares"
Sole dispositive power is the exclusive legal authority to decide what happens to a security — for example, whether to sell, transfer, or retain shares — without needing anyone else’s permission. Investors care because it signals who truly controls the economic outcome of an investment: like holding the only key to a safe, the holder can realize gains or losses and may trigger regulatory reporting, insider rules, or influence over corporate ownership.
Schedule 13G/Aregulatory
"Amendment No. 2 ) Sutro Biopharma, Inc. Common stock"
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.
FAQ
AI-generated questions and answers. How Rhea-AI works. Not financial advice.
What stake does Affinity Asset Advisors report in Sutro Biopharma (STRO)?
Affinity Asset Advisors and Michael Cho report beneficial ownership of 1,069,519 shares, approximately 6.5% of Sutro's common stock as of March 31, 2026.
How was the 6.5% ownership percentage calculated for STRO?
The percentage is based on 16,567,762 shares outstanding as of March 31, 2026, per the issuer's Definitive Proxy Statement filed April 22, 2026.
What voting and dispositive powers are reported by the filers?
The filing states the Reporting Persons have sole power to vote and sole power to dispose of all 1,069,519 shares reported as of March 31, 2026.
Who holds the shares reported in the Schedule 13G/A filing?
The securities are directly held by Affinity Healthcare Fund, LP; Affinity Asset Advisors is the fund's investment manager and Michael Cho is the Adviser's managing member and a deemed beneficial owner.
Does the filing indicate any change in control or activist intent?
The amendment reports beneficial ownership only and does not state any change of control or activist intentions; no further intentions are disclosed in the provided excerpt.
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 2)
Sutro Biopharma, Inc.
(Name of Issuer)
Common stock, $0.001 par value per share
(Title of Class of Securities)
869367201
(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):
869367201
1
Names of Reporting Persons
Affinity Asset 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
1,069,519.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
1,069,519.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,069,519.00
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)
6.5 %
12
Type of Reporting Person (See Instructions)
IA, OO
SCHEDULE 13G
CUSIP Number(s):
869367201
1
Names of Reporting Persons
Michael Cho
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
1,069,519.00
6
Shared Voting Power
0.00
7
Sole Dispositive Power
1,069,519.00
8
Shared Dispositive Power
0.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
1,069,519.00
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)
6.5 %
12
Type of Reporting Person (See Instructions)
IN, HC
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Sutro Biopharma, Inc.
(b)
Address of issuer's principal executive offices:
111 Oyster Point Blvd., South San Franciso, California, 94080
Item 2.
(a)
Name of person filing:
Affinity Asset Advisors, LLC
Michael Cho
(b)
Address or principal business office or, if none, residence:
450 Park Avenue
Suite 1403
New York, NY 10022
(c)
Citizenship:
Affinity Asset Advisors, LLC is a Delaware limited liability company, and Michael Cho is an individual and is a citizen of the United States.
(d)
Title of class of securities:
Common stock, $0.001 par value per share
(e)
CUSIP No.:
869367201
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 securities reported herein are directly held by Affinity Healthcare Fund, LP (the "Fund"). Affinity Asset Advisors, LLC (the "Adviser") is the investment manager of the Fund and exercises voting and investment power over the securities held directly by the Fund reported herein pursuant to an investment management agreement between the Adviser, the Fund, and the general partner of the Fund. The Adviser may be deemed to beneficially own the securities reported herein held by the Fund by virtue of its position as investment manager of the Fund. Michael Cho, the managing member of the Adviser, may be deemed a beneficial owner of the securities reported herein held directly by the Fund.
As of March 31, 2026, the Adviser and Mr. Cho (collectively, the "Reporting Persons") beneficially own 1,069,519 shares of common stock, par value $0.001 per share ("Common Stock"), of Sutro Biopharma, Inc. (the "Issuer").
(b)
Percent of class:
As of March 31, 2026, the Reporting Persons beneficially own approximately 6.5% of the Common Stock outstanding
The percentages disclosed above are based on 16,567,762 shares of Common Stock of the Issuer outstanding as of March 31, 2026, as set forth in the Issuer's Definitive Proxy Statement filed with the Securities and Exchange Commission on April 22, 2026.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
As of March 31, 2026, the Reporting Persons have sole power to vote or to direct the vote of 1,069,519 shares of Common Stock
(ii) Shared power to vote or to direct the vote:
As of March 31, 2026, the Reporting Persons have shared power to vote or to direct the vote of 0 shares of Common Stock.
(iii) Sole power to dispose or to direct the disposition of:
As of March 31, 2026, the Reporting Persons have sole power to dispose or to direct the disposition of 1,069,519 shares of Common Stock.
(iv) Shared power to dispose or to direct the disposition of:
As of March 31, 2026, the Reporting Persons have shared power to dispose or to direct the disposition of 0 shares of Common Stock.
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 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.
Affinity Asset Advisors, LLC
Signature:
/s/ Andrew Weinstein
Name/Title:
Andrew Weinstein, Chief Financial Officer and Chief Compliance Officer
