Abivax (ABVX): TCG Crossover and Chen Yu report 7.0% ADS stake

Rhea-AI Filing Summary

Abivax SA is reported to have significant ownership by TCG Crossover investment entities and Chen Yu through American Depositary Shares (ADSs), each representing one ordinary share. TCG Crossover Fund I, L.P. and its general partner TCG Crossover GP I, LLC report beneficial ownership of 4,924,377 ADSs, or 5.7% of Abivax’s ordinary shares outstanding. TCG Crossover Fund II, L.P. and TCG Crossover GP II, LLC report 1,083,457 ADSs, or 1.3%. Chen Yu, as sole managing member of both general partners, may be deemed to share voting and dispositive power over an aggregate 6,007,834 ADSs, representing 7.0% of the class, based on 86,094,535 shares outstanding as of July 2, 2026, following an underwritten offering. The reporting parties collectively disclaim group status and beneficial ownership beyond their pecuniary interests.

Key Figures

Shares outstanding: 86,094,535 shares TCG Crossover I holdings: 4,924,377 ADSs TCG Crossover II holdings: 1,083,457 ADSs +4 more

7 metrics

Shares outstanding 86,094,535 shares Ordinary shares outstanding as of July 2, 2026 following an underwritten offering

TCG Crossover I holdings 4,924,377 ADSs Abivax ordinary shares in ADS form held of record by TCG Crossover I; 5.7% of class

TCG Crossover II holdings 1,083,457 ADSs Abivax ordinary shares in ADS form held of record by TCG Crossover II; 1.3% of class

Chen Yu aggregate holdings 6,007,834 ADSs Aggregate Abivax ADSs over which Chen Yu may be deemed to share voting and dispositive power; 7.0% of class

Ownership percentage TCG Crossover I 5.7% Percent of Abivax ordinary shares beneficially owned via 4,924,377 ADSs

Ownership percentage TCG Crossover II 1.3% Percent of Abivax ordinary shares beneficially owned via 1,083,457 ADSs

Ownership percentage Chen Yu 7.0% Percent of Abivax ordinary shares represented by 6,007,834 ADSs

Key Terms

American Depositary Shares, beneficial ownership, pecuniary interest, dispositive power, +1 more

5 terms

American Depositary Shares financial

"Consists of ordinary shares in the form of American Depositary Shares ("ADSs") of the Issuer"

American depositary shares (ADSs) are a way for investors in the United States to buy shares of foreign companies without dealing with international markets directly. They represent ownership in a foreign company's stock and are traded on U.S. stock exchanges, making it easier for American investors to buy, sell, and own parts of companies from around the world.

beneficial ownership financial

"Each of the Reporting Persons disclaims beneficial ownership as to such securities"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

pecuniary interest financial

"disclaims beneficial ownership of all securities reported ... except to the extent of such Reporting Person's pecuniary interest"

dispositive power financial

"may be deemed to have voting, investment, and dispositive power with respect to these securities"

Dispositive power is the authority to decide the final outcome of an asset, legal claim, contract, or corporate action — in effect the power to dispose of or resolve something. For investors it matters because whoever holds that authority can determine who gets paid, who controls an asset or vote, and how risks and returns are allocated; think of it like holding the key that lets you lock in the winner or loser in a deal.

underwritten offering financial

"Based on 86,094,535 shares of Common Stock outstanding ... following the underwritten offering that closed on July 2, 2026"

An underwritten offering is when a bank or group of banks agrees to buy all of a company's new shares or bonds and then resell them to outside investors, guaranteeing the company will raise a specific amount of money. It matters to investors because it adds certainty that the funding will close while increasing the number of shares or debt in the market, which can lower the price per share and change each existing owner's ownership percentage—think of a wholesaler buying an entire shipment from a maker before it reaches stores.

FAQ

How large is TCG Crossover Fund I’s stake in Abivax (ABVX)?

TCG Crossover Fund I and its general partner report 4,924,377 ADSs of Abivax, representing 5.7% of the outstanding ordinary shares, based on 86,094,535 shares outstanding as of July 2, 2026 following an underwritten offering.

What percentage of Abivax (ABVX) is reported as beneficially owned by Chen Yu?

Chen Yu may be deemed to beneficially own 6,007,834 ADSs of Abivax, representing 7.0% of the ordinary shares, through interests in TCG Crossover I and II, based on 86,094,535 shares outstanding as of July 2, 2026.

How many Abivax (ABVX) shares does TCG Crossover Fund II report holding?

TCG Crossover Fund II and its general partner report holding 1,083,457 ADSs of Abivax, equal to 1.3% of the ordinary shares outstanding, calculated against 86,094,535 shares outstanding as of July 2, 2026 following the offering.

What is the total Abivax (ABVX) share count used in this Schedule 13G/A?

The ownership percentages are calculated using 86,094,535 Abivax ordinary shares outstanding as of July 2, 2026, following an underwritten offering, as reported by Abivax in a prospectus filed with the Commission on that date.

Do the TCG Crossover entities file as a group for their Abivax (ABVX) holdings?

The TCG Crossover entities and Chen Yu jointly file this ownership report but expressly disclaim status as a group and also disclaim beneficial ownership of reported securities except to the extent of their pecuniary interests in those securities.

How are Abivax (ABVX) ordinary shares held by the reporting persons?

The reporting persons’ positions consist of Abivax ordinary shares held in the form of American Depositary Shares (ADSs). Each ADS represents one ordinary share, and these ADSs are held of record by TCG Crossover I and TCG Crossover II.

AI-generated analysis. How Rhea-AI works. Not financial advice.

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 08/14/2026 - 04:29 PM Accepted by SEC EDGAR 08/14/2026 - 04:22 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

Abivax SA

(Name of Issuer)

Ordinary Shares, par value Euro 0.01 per share

(Title of Class of Securities)

00370M103

(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): 00370M103

1

Names of Reporting Persons

TCG Crossover GP I, 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 0.00
6	Shared Voting Power 4,924,377.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,924,377.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,924,377.00

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)

5.7 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: Consists of 4,924,377 ordinary shares (as defined in Item 2(d) below) in the form of American Depositary Shares ("ADSs") of the Issuer (as defined in Item 1(a) below) held of record by TCG Crossover I (as defined in Item 2(a) below). Each ADS represents one (1) ordinary share. TCG Crossover GP I (as defined in Item 2(a) below) is the general partner of TCG Crossover I and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP I and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 86,094,535 shares of Common Stock outstanding as of July 2, 2026, following the underwritten offering that closed on July 2, 2026 (the Offering), as reported by the Issuer in its prospectus filed with the United States Securities and Exchange Commission (the Commission) on July 2, 2026 (the Prospectus).

SCHEDULE 13G

CUSIP Number(s): 00370M103

1

Names of Reporting Persons

TCG Crossover Fund I, L.P.

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 4,924,377.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 4,924,377.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,924,377.00

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)

5.7 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: Consists of 4,924,377 ordinary shares in the form of ADSs of the Issuer held of record by TCG Crossover I. Each ADS represents one (1) ordinary share. TCG Crossover GP I is the general partner of TCG Crossover I and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP I and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 86,094,535 shares of Common Stock outstanding as of July 2, 2026, following the Offering, as reported by the Issuer in the Prospectus.

SCHEDULE 13G

CUSIP Number(s): 00370M103

1

Names of Reporting Persons

TCG Crossover GP II, 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 0.00
6	Shared Voting Power 1,083,457.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,083,457.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,083,457.00

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)

1.3 %

12

Type of Reporting Person (See Instructions)

OO

Comment for Type of Reporting Person: Consists of 1,083,457 ordinary shares in the form of ADSs of the Issuer held of record by TCG Crossover II (as defined in Item 2(a) below). Each ADS represents one (1) ordinary share. TCG Crossover GP II (as defined in Item 2(a) below) is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 86,094,535 shares of Common Stock outstanding as of July 2, 2026, following the Offering, as reported by the Issuer in the Prospectus.

SCHEDULE 13G

CUSIP Number(s): 00370M103

1

Names of Reporting Persons

TCG Crossover Fund II, L.P.

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 1,083,457.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 1,083,457.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

1,083,457.00

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)

1.3 %

12

Type of Reporting Person (See Instructions)

PN

Comment for Type of Reporting Person: Consists of 1,083,457 ordinary shares in the form of ADSs of the Issuer held of record by TCG Crossover II. Each ADS represents one (1) ordinary share. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to these securities. Chen Yu is the sole managing member of TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to these securities. Based on 86,094,535 shares of Common Stock outstanding as of July 2, 2026, following the Offering, as reported by the Issuer in the Prospectus.

SCHEDULE 13G

CUSIP Number(s): 00370M103

1

Names of Reporting Persons

Chen Yu

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 6,007,834.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 6,007,834.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

6,007,834.00

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)

7.0 %

12

Type of Reporting Person (See Instructions)

IN

Comment for Type of Reporting Person: Consists of (i) 4,924,377 ordinary shares in the form of ADSs of the Issuer held of record by TCG Crossover I and (ii) 1,083,457 ordinary shares in the form of ADSs of the Issuer held of record by TCG Crossover II. TCG Crossover GP I is the general partner of TCG Crossover I and may be deemed to have voting, investment, and dispositive power with respect to the securities held of record by TCG Crossover I. TCG Crossover GP II is the general partner of TCG Crossover II and may be deemed to have voting, investment, and dispositive power with respect to the securities held of record by TCG Crossover II. Chen Yu is the sole managing member of each of TCG Crossover GP I and TCG Crossover GP II and may be deemed to share voting, investment and dispositive power with respect to the securities held of record by TCG Crossover II and TCG Crossover II. Based on 86,094,535 shares of Common Stock outstanding as of July 2, 2026, following the Offering, as reported by the Issuer in the Prospectus.

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Abivax SA
(b)	Address of issuer's principal executive offices: 7-11 boulevard Haussman, Paris, France, 75009
Item 2.
(a)	Name of person filing: This Amendment No. 2 (Amendment No. 2) amends and supplements the Schedule 13G initially filed with the Commission on April 19, 2024, as amended by Amendment No. 1 filed with the Commission on November 14, 2025 (the Original Schedule 13G) and is being filed by TCG Crossover Fund I, L.P. (TCG Crossover I), TCG Crossover GP I, LLC (TCG Crossover GP I), TCG Crossover Fund II, L.P. (TCG Crossover II) and TCG Crossover GP II, LLC (TCG Crossover GP II and together with TCG Crossover I, TCG Crossover GP I and TCG Crossover II, the Reporting Entities) and Chen Yu (the Reporting Individual). The Reporting Entities and the Reporting Individual are collectively referred to as the Reporting Persons. The Reporting Persons expressly disclaim status as a group for purposes of this Schedule 13G. The agreement among the Reporting Persons to file jointly in accordance with the provisions of Rule 13d-1(k)(1) under the Act is attached as Exhibit 2 to the Original Schedule 13G. Other than those securities reported herein as being held directly by such Reporting Person, each Reporting Person disclaims beneficial ownership of all securities reported in this Amendment No. 2 except to the extent of such Reporting Person's pecuniary interest therein.
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each Reporting Person is 245 Lytton Ave., Suite 350, Palo Alto, CA 94301.
(c)	Citizenship: TCG Crossover GP I and TCG Crossover GP II are each a limited liability company organized under the laws of the State of Delaware. TCG Crossover I and TCG Crossover II are each a limited partnership organized under the laws of the State of Delaware. The Reporting Individual is a citizen of the United States of America.
(d)	Title of class of securities: Ordinary Shares, par value Euro 0.01 per share
(e)	CUSIP No.: 00370M103
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: See Row 9 of the cover page for each Reporting Person and the corresponding footnotes. Each of the Reporting Persons disclaims beneficial ownership as to such securities, except to the extent of his or its pecuniary interest therein.
(b)	Percent of class: See Row 11 of the cover page for each Reporting Person and the corresponding footnotes. Each of the Reporting Persons disclaims beneficial ownership as to such securities, except to the extent of his or its pecuniary interest therein.
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: See Row 5 of the cover page for each Reporting Person and the corresponding footnotes. Each of the Reporting Persons disclaims beneficial ownership as to such securities, except to the extent of his or its pecuniary interest therein.
	(ii) Shared power to vote or to direct the vote: See Row 6 of the cover page for each Reporting Person and the corresponding footnotes. Each of the Reporting Persons disclaims beneficial ownership as to such securities, except to the extent of his or its pecuniary interest therein.
	(iii) Sole power to dispose or to direct the disposition of: See Row 7 of the cover page for each Reporting Person and the corresponding footnotes. Each of the Reporting Persons disclaims beneficial ownership as to such securities, except to the extent of his or its pecuniary interest therein.
	(iv) Shared power to dispose or to direct the disposition of: See Row 8 of the cover page for each Reporting Person and the corresponding footnotes. Each of the Reporting Persons disclaims beneficial ownership as to such securities, except to the extent of his or its pecuniary interest therein.
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. Under certain circumstances set forth in the limited partnership agreements of TCG Crossover I and TCG Crossover II and the limited liability company agreements of TCG Crossover GP I and TCG Crossover GP II, the general and limited partners or members, as the case may be, of each of such entities may be deemed to have the right to receive dividends from, or the proceeds from, the sale of securities of the Issuer owned by each such entity of which they are a partner or member, as the case may be.
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 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.

TCG Crossover GP I, LLC

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	08/14/2026

TCG Crossover Fund I, L.P.

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	08/14/2026

TCG Crossover GP II, LLC

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	08/14/2026

TCG Crossover Fund II, L.P.

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, Authorized Signatory
Date:	08/14/2026

Chen Yu

Signature:	/s/ Craig Skaling
Name/Title:	Craig Skaling, as Attorney-in-Fact for Chen Yu
Date:	08/14/2026