NovaBridge Biosciences: Hillhouse reports 4.9% stake

The 4.9% ownership figure is calculated against 270,740,383 ordinary shares outstanding as of July 27, 2026.

Available on EDGAR 11/05/2026 - 09:42 PM EST Accepted by SEC EDGAR 11/05/2026 - 09:41 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

NovaBridge Biosciences (NBP) is the issuer named in a final amendment by reporting persons HHLR Advisors, Ltd. and Hillhouse Investment Management, Ltd. They reported shared voting and dispositive power over 13,295,306 ordinary shares, representing 4.9%; the shares are held by funds managed by HHLR and correspond to 5,780,568 ADSs. The reporting persons identified this as their final amendment and an exit filing.

Key Figures

Beneficially owned: 13,295,306 ordinary shares Ownership percentage: 4.9% ADSs held: 5,780,568 ADSs +2 more

5 metrics

Beneficially owned 13,295,306 ordinary shares Reported by each reporting person as shared voting and dispositive power

Ownership percentage 4.9% Percentage of ordinary shares

ADSs held 5,780,568 ADSs Held by funds managed by HHLR

Ordinary shares outstanding 270,740,383 ordinary shares As of July 27, 2026; basis for the ownership percentage

ADS conversion ratio 10 ADSs represent 23 ordinary shares Each ADS represents ordinary shares

Key Terms

beneficially owned, Shared Voting Power, Shared Dispositive Power, American Depositary Shares, +1 more

5 terms

beneficially owned financial

"aggregate amount beneficially owned by each reporting person"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Shared Voting Power technical

"Shared Voting Power 13,295,306.00"

Shared voting power occurs when two or more parties jointly have the right to vote or decide how a block of company shares is cast, like co-owners who must agree before moving a piece of furniture. Investors care because who controls voting rights affects board elections, major corporate decisions and takeover outcomes, and shared control can alter regulatory disclosures and the practical influence any holder has over a company’s direction and value.

Shared Dispositive Power technical

"Shared Dispositive Power 13,295,306.00"

American Depositary Shares financial

"American Depositary Shares ("ADSs")"

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.

exit filing regulatory

"constitutes an "exit filing" for each of the Reporting Persons"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

How many NBP ordinary shares do HHLR Advisors and Hillhouse Investment Management report?

HHLR Advisors, Ltd. and Hillhouse Investment Management, Ltd. each report shared voting and dispositive power over 13,295,306 ordinary shares, equal to 4.9%.

What is the NBP ADS conversion ratio?

Each 10 ADSs represents 23 ordinary shares.

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

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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 6)

NovaBridge Biosciences

(Name of Issuer)

Ordinary Shares, par value $0.0001 per share

(Title of Class of Securities)

44975P103

(CUSIP Number)

Richard A. Hornung
Office #122, Windward 3 Building, Regatta Office Park, West Bay Road
Grand Cayman, E9, KY1-9006
656-603-0860

Adriana Schwartz
Seward & Kissel LLP, One Battery Park Plaza
New York, NY, 10004
212-574-1200

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

11/05/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

schemaVersion:

SCHEDULE 13D

CUSIP Number(s): 44975P103

1

Name of reporting person

HHLR Advisors, Ltd.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 13,295,306.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 13,295,306.00

11

Aggregate amount beneficially owned by each reporting person

13,295,306.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.9 %

14

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person:

Consists of 5,780,568 ADSs representing 13,295,306 Ordinary Shares held by funds managed by HHLR. HHLR and HIM are under common control and share certain policies, personnel and resources.

SCHEDULE 13D

CUSIP Number(s): 44975P103

1

Name of reporting person

Hillhouse Investment Management, Ltd.

2

Check the appropriate box if a member of a Group (See Instructions)

(a)
(b)

3

SEC use only

4

Source of funds (See Instructions)

AF

5

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

6

Citizenship or place of organization

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 13,295,306.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 13,295,306.00

11

Aggregate amount beneficially owned by each reporting person

13,295,306.00

12

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

13

Percent of class represented by amount in Row (11)

4.9 %

14

Type of Reporting Person (See Instructions)

IA

Comment for Type of Reporting Person:

Consists of 5,780,568 ADSs representing 13,295,306 Ordinary Shares held by funds managed by HHLR. HHLR and HIM are under common control and share certain policies, personnel and resources.

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Ordinary Shares, par value $0.0001 per share
(b)	Name of Issuer: NovaBridge Biosciences
(c)	Address of Issuer's Principal Executive Offices: SUITE 400, 2440 RESEARCH BLVD, ROCKVILLE, MARYLAND , 20850.
Item 1 Comment: This Amendment No. 6 ("Amendment No. 6") amends the statement on Schedule 13D filed with the Securities and Exchange Commission (the "SEC") on September 14, 2020, as amended by Amendment No. 1 filed on December 21, 2021 with the SEC, Amendment No. 2 filed on March 25, 2021 with the SEC, Amendment No. 3 filed on June 24, 2021 with the SEC, Amendment No. 4 filed on September 27, 2021 with the SEC, Amendment No. 5 filed on June 30, 2023 with the SEC, and as amended hereby (the "Schedule 13D"), with respect to the ordinary shares, par value $0.0001 per share (the "Ordinary Shares") of NovaBridge Biosciences (f/k/a I-MAB), an exempted Cayman Islands company (the "Issuer"). Capitalized terms used herein and not otherwise defined in this Amendment No. 6 have the meanings set forth in the Schedule 13D. This Amendment No. 6 amends Items 5(a)-(c) and (e) as set forth below. This Amendment No. 6 is the final amendment to the Schedule 13D and constitutes an "exit filing" for each of the Reporting Persons. There is no CUSIP number assigned to the Ordinary Shares. CUSIP number 44975P103 has been assigned to the American Depositary Shares ("ADSs") of the Issuer, which are quoted on the Nasdaq Global Market under the symbol "NBP." Each 10 ADSs represents 23 Ordinary Shares.
Item 2.	Identity and Background
(a)	See rows (11) and (13) of the cover pages to this Schedule 13D for the aggregate number of Ordinary Shares and percentages of the Ordinary Shares beneficially owned by each Reporting Person. The percentage used in this Schedule 13D is calculated based upon 270,740,383 Ordinary Shares outstanding as of July 27, 2026, as reported in the Issuer's Report of Foreign Private Issuer on Form 6-K filed with the SEC on September 8, 2026.
(b)	See rows (7) through (10) of the cover pages to this Schedule 13D for the number of Ordinary Shares as to which each Reporting Person has the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition.
(c)	Information concerning transactions in the Ordinary Shares (which were in the form of ADS) effected by the Reporting Persons in the last 60 days is set forth in Annex A hereto and is incorporated herein by reference.
(d)	November 5, 2026

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.

HHLR Advisors, Ltd.

Signature:	/s/ Audrey Woon
Name/Title:	Audrey Woon, Chief Compliance Officer
Date:	11/05/2026

Hillhouse Investment Management, Ltd.

Signature:	/s/ Audrey Woon
Name/Title:	Audrey Woon, Chief Compliance Officer
Date:	11/05/2026