[SCHEDULE 13G] Zai Lab Limited American SEC Filing

Rhea-AI Filing Summary

RTW Investments, LP and Roderick Wong reported shared voting and dispositive power over 55,368,760 ordinary shares of Zai Lab Limited (ZLAB), equal to 5.1% of the class. The percentage is calculated using 1,084,743,860 shares outstanding as of May 2, 2025. The shares are held directly by RTW-managed funds (the RTW Funds) and the filing states the holdings are held in the ordinary course of business and not for the purpose of changing or influencing control. RTW Investments is a Delaware limited partnership and Dr. Wong is the Managing Partner and Chief Investment Officer; both report 0 sole voting or dispositive power and 55,368,760 shared voting and dispositive power.

Positive

• Material stake disclosed: RTW Investments and Roderick Wong report beneficial ownership of 55,368,760 ordinary shares, representing 5.1% of Zai Lab based on 1,084,743,860 shares outstanding as of May 2, 2025.
• Holdings held by RTW Funds: Shares are directly held by RTW-managed funds, with RTW Investments acting as investment adviser.
• Filing asserts passive intent: Certification in Item 10 states the securities were acquired and are held in the ordinary course of business and not to change or influence control.

Negative

• No sole voting or dispositive power: Both RTW Investments and Dr. Wong report 0 sole voting power and 0 sole dispositive power, indicating shared rather than exclusive control over the shares.

Insights

Financial Analyst

TL;DR: RTW reports a material passive stake of 5.1% in Zai Lab, held via RTW Funds with shared voting and dispositive power.

The filing documents a >5% ownership position (55,368,760 shares) based on 1,084,743,860 outstanding shares as of May 2, 2025, which is material by regulatory standards but is presented as passive and in the ordinary course of business. The position is held by RTW Funds, with RTW Investments and Dr. Wong reporting shared voting and dispositive power and no sole control. For investors, this signals institutional interest without an explicit intent to influence corporate control, per the certification language in Item 10.

Corporate Governance Expert

TL;DR: A 5.1% reported stake triggers disclosure obligations; the filing asserts passive intent and shows shared, not sole, control.

The Schedule 13G discloses that RTW Investments and Dr. Wong have shared voting and dispositive authority over 55,368,760 shares (5.1%). The filing includes the requisite certification that the securities were acquired and are held in the ordinary course of business and not to influence control, which aligns with Schedule 13G treatment rather than a 13D activist filing. The absence of sole voting or dispositive power is relevant for governance assessment because it indicates no single-party control over voting decisions reported here.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

Zai Lab Limited

(Name of Issuer)

Ordinary Shares, par value $0.000006 per share

(Title of Class of Securities)

98887Q104

(CUSIP Number)

06/30/2025

(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)

SCHEDULE 13G

CUSIP No. 98887Q104

1

Names of Reporting Persons

RTW Investments, 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 55,368,760.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 55,368,760.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

55,368,760.00

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)

5.1 %

12

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13G

CUSIP No. 98887Q104

1

Names of Reporting Persons

Roderick Wong

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 55,368,760.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 55,368,760.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

55,368,760.00

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)

5.1 %

12

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Zai Lab Limited
(b)	Address of issuer's principal executive offices: 314 Main Street, 4th Floor, Suite 100, Cambridge, MA, 02142.
Item 2.
(a)	Name of person filing: This statement is filed by: (i) RTW Investments, LP ("RTW Investments"), a Delaware limited partnership and the investment adviser to certain funds (the "RTW Funds"), with respect to the Ordinary Shares, par value $0.000006 per share (the "Shares") of Zai Lab Limited (the "Issuer") directly held by the RTW Funds; and (ii) Roderick Wong, M.D. ("Dr. Wong"), the Managing Partner and Chief Investment Officer of RTW Investments, with respect to the Shares directly held by the RTW Funds. 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, as amended, the beneficial owner of the Shares reported herein.
(b)	Address or principal business office or, if none, residence: The address of the business office of each of the Reporting Persons is 40 10th Avenue, Floor 7, New York, New York 10014.
(c)	Citizenship: RTW Investments is a Delaware limited partnership. Dr. Wong is a citizen of the United States.
(d)	Title of class of securities: Ordinary Shares, par value $0.000006 per share
(e)	CUSIP No.: 98887Q104
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: There is no CUSIP number assigned to the Shares. CUSIP number 98887Q104 has been assigned to the American Depositary Shares ("ADSs") of the Issuer. Each ADS represents ten Shares. The information required by Item 4(a) is set forth in Rows 5 - 9 of the cover page for each of the Reporting Persons and is incorporated herein by reference. The percentage set forth in Row 11 of each cover page is calculated based upon 1,084,743,860 Shares outstanding as of May 2, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (the "SEC") on May 8, 2025.
(b)	Percent of class: RTW Investments: 5.1% Dr. Wong: 5.1%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: RTW Investments: 0 Dr. Wong: 0
	(ii) Shared power to vote or to direct the vote: RTW Investments: 55,368,760 Shares Dr. Wong: 55,368,760 Shares
	(iii) Sole power to dispose or to direct the disposition of: RTW Investments: 0 Dr. Wong: 0
	(iv) Shared power to dispose or to direct the disposition of: RTW Investments: 55,368,760 Shares Dr. Wong: 55,368,760 Shares
Item 5.	Ownership of 5 Percent or Less of a Class.
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. The RTW Funds have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, the Shares reported herein.
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.

RTW Investments, LP

Signature:	/s/ Roderick Wong, M.D.
Name/Title:	By Roderick Wong, M.D., Managing Partner
Date:	08/14/2025

Roderick Wong

Signature:	/s/ Roderick Wong, M.D.
Name/Title:	Roderick Wong, M.D.
Date:	08/14/2025

Exhibit Information

Exhibit 99.1 Joint Filing Agreement

FAQ

What stake does RTW Investments hold in Zai Lab (ZLAB)?

RTW Investments and Roderick Wong report beneficial ownership of 55,368,760 ordinary shares, representing 5.1% of the class.

How was the 5.1% ownership percentage calculated?

The percentage is based on 1,084,743,860 shares outstanding as of May 2, 2025, as reported in Zai Lab's quarterly report filed with the SEC.

Does RTW or Dr. Wong have sole voting or dispositive power over the shares?

No. The filing reports 0 sole voting power and 0 sole dispositive power for both RTW Investments and Roderick Wong, and 55,368,760 shares of shared voting and dispositive power.

Are the shares held for activism or to influence control of Zai Lab?

According to the certification in Item 10, the securities were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of changing or influencing control of the issuer.

Who holds the shares on behalf of RTW Investments?

The shares are directly held by the RTW Funds, for which RTW Investments serves as the investment adviser, and RTW Funds have the right to receive dividends or proceeds from sale.