Equillium, Inc. Schedule 13G/A: ADAR1-related entities and Daniel Schneeberger report indirect beneficial ownership of common stock as of March 31, 2026. ADAR1 Capital Management, LLC is shown with 6,603,754 shares (9.9%); ADAR1 Capital Management GP, LLC with 6,306,184 shares (9.5%). The filing cites 63,226,556 shares outstanding as of March 31, 2026 per the issuer's Form 10-Q. The cover disclosures list constituent holdings and 2,877,095 shares underlying prefunded warrants, and note 557,415 prefunded-warrant shares excluded due to a 9.99% beneficial ownership limitation. The filing states these holdings are indirect, reflecting ADAR1’s roles as investment manager, general partner, and Mr. Schneeberger’s manager/control-person status.
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Insights
ADAR1 group holds just under double‑digit stakes in Equillium based on March 31, 2026 outstanding shares.
Documented holdings show 6,603,754 shares (9.9%) for ADAR1 Capital Management and 6,306,184 shares (9.5%) for ADAR1 Capital Management GP, based on 63,226,556 shares outstanding. The positions include common stock and substantial prefunded warrant exposure of 2,877,095 shares.
Ownership is described as indirect through managed funds and SPVs, and the filing notes a 9.99% beneficial ownership limitation that excludes 557,415 prefunded‑warrant shares. Subsequent filings or conversions could change reported percentages if and when exchanges occur.
Key Figures
ADAR1 Capital Management holdings:6,603,754 sharesADAR1 Capital Management GP holdings:6,306,184 sharesShares outstanding used:63,226,556 shares+2 more
5 metrics
ADAR1 Capital Management holdings6,603,754 sharesreported as 9.9% of class as of March 31, 2026
ADAR1 Capital Management GP holdings6,306,184 sharesreported as 9.5% of class as of March 31, 2026
Shares outstanding used63,226,556 sharesoutstanding as of March 31, 2026 per issuer Form 10‑Q
Prefunded warrants included2,877,095 sharesshares underlying prefunded warrants included in reported holdings
Prefunded warrants excluded557,415 sharesexcluded due to 9.99% beneficial ownership limitation
Key Terms
prefunded warrants, beneficial ownership limitation, Schedule 13G/A, indirect beneficially own
4 terms
prefunded warrantsfinancial
"2,877,095 shares of Common Stock underlying prefunded warrants held by ADAR1 Partners"
Prefunded warrants are a security that gives the holder the right to convert the warrant into a share after paying a very small remaining amount because almost the full purchase price was paid upfront. They matter to investors because exercising them increases the company’s outstanding shares (dilution) and can provide immediate cash to the issuer while allowing holders to bypass ownership limits or simplify timing, similar to buying a nearly-complete gift card that only needs a tiny top-up to use.
beneficial ownership limitationregulatory
"exchange and exercise of which are subject to 9.99% beneficial ownership limitations"
A beneficial ownership limitation is a rule that caps the percentage of a company’s shares an investor can be treated as owning or controlling for voting, regulatory or tax purposes. It matters to investors because it can restrict how many shares a person or group can buy or vote, affect takeover chances, and influence share liquidity and value — like a speed limit that prevents any single driver from taking over the whole road.
Schedule 13G/Aregulatory
"This Schedule is being filed on behalf of each of the following persons"
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.
indirect beneficially ownregulatory
"may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP"
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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
SCHEDULE 13G
UNDER THE SECURITIES EXCHANGE ACT OF 1934
(Amendment No. 1)
Equillium, Inc.
(Name of Issuer)
Common Stock, par value $0.0001 per share
(Title of Class of Securities)
29446K106
(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):
29446K106
1
Names of Reporting Persons
ADAR1 Capital Management, 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
TEXAS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
6,603,754.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
6,603,754.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,603,754.00
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)
9.9 %
12
Type of Reporting Person (See Instructions)
IA, OO
Comment for Type of Reporting Person: Includes (i) 2,786,136 shares of common stock, par value $0.0001 per share ("Common Stock") held by ADAR1 Partners, LP, (ii) 404,699 shares of Common Stock held by Spearhead Insurance Solutions IDF, LLC, (iii) 533,742 shares of Common Stock held by ADAR1 SPV I, LP, (iv) 2,082 shares of Common Stock held by other separately managed accounts and (v) 2,877,095 shares of Common Stock underlying prefunded warrants held by ADAR1 Partners, LP, ADAR1 SPV I, LP and Spearhead Insurance Solutions IDF, LLC as of March 31, 2026. Excludes 557,415 shares of Common Stock underlying prefunded warrants held by ADAR1 Partners, LP, ADAR1 SPV I, LP and Spearhead Insurance Solutions IDF, LLC, the exchange and exercise of which are subject to 9.99% beneficial ownership limitations. As the investment manager of ADAR1 Partners, LP and ADAR1 SPV I, LP and as the sub-advisor of Spearhead Insurance Solutions IDF, LLC and the separately managed accounts referenced above, ADAR1 Capital Management, LLC may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP; Spearhead Insurance Solutions IDF, LLC; ADAR1 SPV I, LP and the separately managed accounts.
Based on 63,226,556 shares of Common Stock of Equillium Inc. (the "Issuer") outstanding as of March 31, 2026, reported in the Issuer's Form 10Q for the quarterly period ended March 31, 2026, filed with the Securities and Exchange Commission on May 13, 2026.
SCHEDULE 13G
CUSIP Number(s):
29446K106
1
Names of Reporting Persons
ADAR1 Capital Management 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
TEXAS
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
6,306,184.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
6,306,184.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,306,184.00
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)
9.5 %
12
Type of Reporting Person (See Instructions)
OO
Comment for Type of Reporting Person: Includes (i) 2,786,136 shares of common stock, par value $0.0001 per share ("Common Stock") held by ADAR1 Partners, LP, (ii) 533,742 shares of Common Stock held by ADAR1 SPV I, LP and (iii) 2,986,306 shares of Common Stock underlying prefunded warrants held by ADAR1 Partners, LP and ADAR1 SPV I, LP as of March 31, 2026. As the general partner of ADAR1 Partners, LP and ADAR1 SPV I, LP, ADAR1 Capital Management GP, LLC may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP and ADAR1 SPV I, LP.
Based on 63,226,556 shares of Common Stock of Equillium Inc. (the "Issuer") outstanding as of March 31, 2026, reported in the Issuer's Form 10Q for the quarterly period ended March 31, 2026, filed with the Securities and Exchange Commission on May 13, 2026.
SCHEDULE 13G
CUSIP Number(s):
29446K106
1
Names of Reporting Persons
Daniel Schneeberger
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
SWITZERLAND
Number of Shares Beneficially Owned by Each Reporting Person With:
5
Sole Voting Power
0.00
6
Shared Voting Power
6,603,754.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
6,603,754.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
6,603,754.00
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)
9.9 %
12
Type of Reporting Person (See Instructions)
HC, IN
Comment for Type of Reporting Person: Includes (i) 2,786,136 shares of common stock, par value $0.0001 per share ("Common Stock") held by ADAR1 Partners, LP, (ii) 404,699 shares of Common Stock held by Spearhead Insurance Solutions IDF, LLC, (iii) 533,742 shares of Common Stock held by ADAR1 SPV I, LP, (iv) 2,082 shares of Common Stock held by other separately managed accounts and (v) 2,877,095 shares of Common Stock underlying prefunded warrants held by ADAR1 Partners, LP, ADAR1 SPV I, LP and Spearhead Insurance Solutions IDF, LLC as of March 31, 2026. Excludes 557,415 shares of Common Stock underlying prefunded warrants held by ADAR1 Partners, LP, ADAR1 SPV I, LP and Spearhead Insurance Solutions IDF, LLC, the exchange and exercise of which are subject to 9.99% beneficial ownership limitations. As the manager of ADAR1 Capital Management, LLC and ADAR1 Capital Management GP, LLC, Mr. Schneeberger may be deemed to indirectly beneficially own securities held by ADAR1 Partners, LP; Spearhead Insurance Solutions IDF, LLC; ADAR1 SPV I, LP; and the separately managed accounts referenced above.
Based on 63,226,556 shares of Common Stock of Equillium Inc. (the "Issuer") outstanding as of March 31, 2026, reported in the Issuer's Form 10Q for the quarterly period ended March 31, 2026, filed with the Securities and Exchange Commission on May 13, 2026.
SCHEDULE 13G
Item 1.
(a)
Name of issuer:
Equillium, Inc.
(b)
Address of issuer's principal executive offices:
2223 Avenida de la Playa, Suite 105 La Jolla, CA 92037
Item 2.
(a)
Name of person filing:
This Schedule is being filed on behalf of each of the following persons (each, a "Reporting Person" and collectively, the "Reporting Persons"):
(i) ADAR1 Capital Management, LLC ("ADAR1 Capital Management");
(ii) ADAR1 Capital Management GP, LLC ("ADAR1 General Partner"); and
(iii) Daniel Schneeberger ("Mr. Schneeberger").
(b)
Address or principal business office or, if none, residence:
The address of the principal business office of each of the Reporting Persons is 3503 Wild Cherry Drive, Building 9, Austin, Texas 78738.
(c)
Citizenship:
(i) ADAR1 Capital Management is a Texas limited liability company;
(ii) ADAR1 General Partner is a Texas limited liability company; and
(iii) Mr. Schneeberger is a citizen of Switzerland.
(d)
Title of class of securities:
Common Stock, par value $0.0001 per share
(e)
CUSIP No.:
29446K106
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 contained on the cover pages of this Schedule 13G is incorporated herein by reference.
(b)
Percent of class:
The information contained on the cover pages of this Schedule 13G is incorporated herein by reference.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
The information contained on the cover pages of this Schedule 13G is incorporated herein by reference.
(ii) Shared power to vote or to direct the vote:
The information contained on the cover pages of this Schedule 13G is incorporated herein by reference.
(iii) Sole power to dispose or to direct the disposition of:
The information contained on the cover pages of this Schedule 13G is incorporated herein by reference.
(iv) Shared power to dispose or to direct the disposition of:
The information contained on the cover pages of this Schedule 13G 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.
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.
Mr. Schneeberger is filing this Schedule 13G as a control person in respect of shares beneficially owned by ADAR1 Capital Management, an investment adviser as described in SS 240.13d-1(b)(1)(ii)(E).
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.
What stake does ADAR1 Capital Management report in Equillium (EQ)?
ADAR1 Capital Management reports 6,603,754 shares, or 9.9%, of Equillium common stock as of March 31, 2026, including common stock and prefunded‑warrant exposure described in the filing.
How many shares outstanding does Equillium report used in the ownership calculation?
The filing references 63,226,556 shares outstanding as of March 31, 2026, drawn from Equillium's Form 10‑Q for the quarter ended March 31, 2026.
Do the reported holdings include prefunded warrants?
Yes. The cover pages list 2,877,095 shares underlying prefunded warrants included in the reported holdings and note 557,415 prefunded‑warrant shares are excluded due to a 9.99% beneficial ownership limitation.
Why are the holdings described as indirect for ADAR1 and Mr. Schneeberger?
The filing states ADAR1 entities act as investment manager, general partner, or sub‑advisor to funds and accounts, so ADAR1 Capital Management and Mr. Schneeberger may be deemed to indirectly beneficially own the securities held by those entities.
What percent does ADAR1 Capital Management GP, LLC report owning?
ADAR1 Capital Management GP, LLC reports 6,306,184 shares, or 9.5%, of Equillium common stock as of March 31, 2026, per the Schedule 13G/A cover data.
