| 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);
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| (b) | Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
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| (c) | Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
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| (d) | Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
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| (e) |  An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
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| (f) | An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
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| (g) | A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
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| (h) | A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
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| (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);
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| (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:
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| (k) | Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
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| 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
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| | (ii) Shared power to vote or to direct the vote:
RTW Investments: 55,368,760 Shares
Dr. Wong: 55,368,760 Shares
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| | (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
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| Item 5. | Ownership of 5 Percent or Less of a Class. |
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| Item 6. | Ownership of more than 5 Percent on Behalf of Another Person. |
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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. |
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Not Applicable
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| Item 8. | Identification and Classification of Members of the Group. |
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Not Applicable
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| Item 9. | Notice of Dissolution of Group. |
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Not Applicable
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