Zai Lab Limited filed a Schedule 13G reporting beneficial ownership of 57,435,330 ordinary shares, held via 5,743,533 ADSs (each ADS = ten ordinary shares). The stake represents 5.2% of shares outstanding based on 1,106,407,390 ordinary shares outstanding as of Feb 20, 2026. The holdings are reported by RA Capital Management, L.P., RA Capital Healthcare Fund, L.P., and related individuals; voting and dispositive powers are described as shared holdings and certain disclaimers of beneficial ownership appear in the filing.
Positive
None.
Negative
None.
Insights
RA Capital and affiliated persons report a 5.2% position in Zai Lab via ADS holdings.
The filing shows the Fund directly holds 5,743,533 ADSs, equal to 57,435,330 ordinary shares. The report notes delegation of voting and disposal powers to RA Capital and contains disclaimers about beneficial ownership under Section 13(d).
This is a disclosure of passive/beneficial holdings rather than an active transaction; subsequent filings would show any change. Cash‑flow treatment and sale intentions are not stated in the excerpt.
Key Figures
Ordinary shares beneficially owned:57,435,330 sharesADS held by Fund:5,743,533 ADSsPercent of class:5.2%+1 more
4 metrics
Ordinary shares beneficially owned57,435,330 sharesheld via 5,743,533 ADSs
ADS held by Fund5,743,533 ADSseach ADS = 10 ordinary shares
Percent of class5.2%based on 1,106,407,390 shares outstanding as of Feb 20, 2026
Shares outstanding (context)1,106,407,390 ordinary sharesas of Feb 20, 2026
Key Terms
American Depositary Shares (ADSs), Section 13(d), Beneficial ownership, Shared dispositive power
4 terms
American Depositary Shares (ADSs)financial
"The Fund directly holds 5,743,533 American Depositary Shares ("ADSs")"
A U.S.-listed certificate that stands for a specific number of shares in a non‑U.S. company held by a U.S. bank, making the foreign stock tradable on American exchanges in dollars. Think of it like a local voucher that represents ownership of an overseas product — it lets U.S. investors buy and sell foreign companies without handling foreign currency or foreign brokerage accounts, but it can affect dividends, voting rights, fees, liquidity and exposure to currency and regulatory differences.
Section 13(d)regulatory
"RA Capital may be deemed a beneficial owner, for purposes of Section 13(d) of the Act"
Beneficial ownershipregulatory
"Amount beneficially owned: CUSIP Number 98887Q104 has been assigned to the ADS of the Issuer"
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.
Shared dispositive powerfinancial
"Shared Dispositive Power 57,435,330.00"
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)
03/30/2026
(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):
98887Q104
1
Names of Reporting Persons
RA Capital Management, 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
57,435,330.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
57,435,330.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
57,435,330.00
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)
5.2 %
12
Type of Reporting Person (See Instructions)
IA, PN
SCHEDULE 13G
CUSIP Number(s):
98887Q104
1
Names of Reporting Persons
Peter Kolchinsky
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
57,435,330.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
57,435,330.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
57,435,330.00
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)
5.2 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
CUSIP Number(s):
98887Q104
1
Names of Reporting Persons
Rajeev Shah
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
57,435,330.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
57,435,330.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
57,435,330.00
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)
5.2 %
12
Type of Reporting Person (See Instructions)
HC, IN
SCHEDULE 13G
CUSIP Number(s):
98887Q104
1
Names of Reporting Persons
RA Capital Healthcare Fund, 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
57,435,330.00
7
Sole Dispositive Power
0.00
8
Shared Dispositive Power
57,435,330.00
9
Aggregate Amount Beneficially Owned by Each Reporting Person
57,435,330.00
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)
5.2 %
12
Type of Reporting Person (See Instructions)
PN
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:
The names of the persons filing this report (collectively, the "Reporting Persons") are:
RA Capital Management, L.P. ("RA Capital")
Peter Kolchinsky ("Dr. Kolchinsky")
Rajeev Shah ("Mr. Shah")
RA Capital Healthcare Fund, L.P. (the "Fund")
The Reporting Persons expressly disclaim status as a "group" for purposes of this Schedule 13G.
(b)
Address or principal business office or, if none, residence:
The address of the principal business office of each of the Reporting Persons is:
c/o RA Capital Management, L.P., 200 Berkeley Street, 18th Floor, Boston MA 02116
(c)
Citizenship:
RA Capital and the Fund are Delaware limited partnerships.
Dr. Kolchinsky and Mr. Shah are United States citizens.
(d)
Title of class of securities:
Ordinary Shares, par value $0.000006 per share
(e)
CUSIP Number(s):
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:
CUSIP Number 98887Q104 has been assigned to the American Depositary Shares ("ADS") of the Issuer, which are quoted on the Nasdaq Global Market under the symbol "ZLAB". No CUSIP has been assigned to the Issuer's ordinary shares.
Row 9 of each Reporting Person's cover page to this Schedule 13G sets forth the aggregate number of ordinary shares of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
The Fund directly holds 5,743,533 American Depositary Shares ("ADSs") of the Issuer, representing an aggregate of 57,435,330 ordinary shares. Each ADS represents ten Ordinary Shares of the Issuer.
RA Capital Healthcare Fund GP, LLC is the general partner of the Fund. The general partner of RA Capital is RA Capital Management GP, LLC, of which Dr. Kolchinsky and Mr. Shah are the controlling persons. RA Capital serves as investment adviser for the Fund and may be deemed a beneficial owner, for purposes of Section 13(d) of the Act, of any securities of the Issuer held by the Fund. The Fund has delegated to RA Capital the sole power to vote and the sole power to dispose of all securities held in the Fund's portfolio, including the ordinary shares of the Issuer reported herein. Because the Fund has divested voting and investment power over the reported securities it holds and may not revoke that delegation on less than 61 days' notice, the Fund disclaims beneficial ownership of the securities it holds for purposes of Section 13(d) of the Act. As managers of RA Capital, Dr. Kolchinsky and Mr. Shah may be deemed beneficial owners, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned by RA Capital. RA Capital, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of the securities reported in this Schedule 13G other than for the purpose of determining their obligations under Section 13(d) of the Act, and the filing of this Schedule 13G shall not be deemed an admission that either RA Capital, Dr. Kolchinsky, or Mr. Shah is the beneficial owner of such securities for any other purpose.
(b)
Percent of class:
Row 11 of each Reporting Person's cover page to this Schedule 13G sets forth the percentages of ordinary shares of the Issuer beneficially owned by such Reporting Person and is incorporated by reference. Such percentage is based upon 1,106,407,390 ordinary shares outstanding as of February 20, 2026, as reported in the Issuer's Annual Report on Form 10-K filed with the Securities and Exchange Commission (the "SEC") on February 26, 2026.
(c)
Number of shares as to which the person has:
(i) Sole power to vote or to direct the vote:
Row 5 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
(ii) Shared power to vote or to direct the vote:
Row 6 of each Reporting Person's cover page to this Schedule 13G sets forth the shared power to vote or to direct the vote of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
(iii) Sole power to dispose or to direct the disposition of:
Row 7 of each Reporting Person's cover page to this Schedule 13G sets forth the sole power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person and is incorporated by reference.
(iv) Shared power to dispose or to direct the disposition of:
Row 8 of each Reporting Person's cover page to this Schedule 13G sets forth the shared power to dispose or to direct the disposition of securities of the Issuer beneficially owned by such Reporting Person and is incorporated 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.
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.
RA Capital Management, L.P.
Signature:
/s/ Peter Kolchinsky
Name/Title:
By Peter Kolchinsky, Authorized Signatory
Date:
04/06/2026
Peter Kolchinsky
Signature:
/s/ Peter Kolchinsky
Name/Title:
Peter Kolchinsky
Date:
04/06/2026
Rajeev Shah
Signature:
/s/ Rajeev Shah
Name/Title:
Rajeev Shah
Date:
04/06/2026
RA Capital Healthcare Fund, L.P.
Signature:
/s/ Peter Kolchinsky
Name/Title:
By RA Capital Healthcare Fund GP, LLC, its General Partner, By Peter Kolchinsky, Manager
What stake in Zai Lab (ZLAB) does RA Capital report?
RA Capital and affiliated entities report ownership of 57,435,330 ordinary shares, held via 5,743,533 ADSs. The filing states this equals 5.2% of the company's ordinary shares based on the issuer's reported outstanding share count.
How is the 57,435,330 share figure derived in the Schedule 13G?
The Fund holds 5,743,533 ADSs, and each ADS represents ten ordinary shares, producing 57,435,330 ordinary shares. The filing states this ADS-to-ordinary share ratio explicitly in Item 4.
What percent of Zai Lab does 57,435,330 shares represent?
The reported stake represents 5.2% of ordinary shares outstanding. That percentage is computed using 1,106,407,390 ordinary shares outstanding as of Feb 20, 2026, cited in the filing.
Who among the reporting persons has voting or dispositive power?
The filing attributes shared voting and shared dispositive power over the reported securities to the reporting entities and individuals. It also discloses delegation of voting and disposal powers from the Fund to RA Capital in the filing.
Does the Schedule 13G say RA Capital intends to sell its Zai Lab shares?
No sale intentions or planned dispositions are disclosed in the provided excerpt. The filing describes voting and dispositive power arrangements and contains disclaimers; it does not state any transaction plans or cash‑flow treatment.
