RTW funds report 39.4% Allurion (ALUR) ownership in 13D amendment

Rhea-AI Filing Summary

Allurion Technologies, Inc. large shareholder RTW-affiliated entities filed an amended Schedule 13D to update their beneficial ownership of the company’s common stock.

RTW Investments, LP and Roderick Wong report beneficial ownership of 5,891,430 shares, representing 39.4% of Allurion’s common stock, with shared voting and dispositive power. RTW Master Fund, Ltd holds 3,138,798 shares (21.0%), and RTW Innovation Master Fund, Ltd holds 2,427,089 shares (16.2%), all on a shared basis.

The ownership percentages are calculated from shares outstanding reported in a January 2026 prospectus plus additional shares issued under an Inducement Offer to Exercise Common Stock Purchase Warrants that closed on February 26, 2026. The filing states that no transactions in Allurion securities were made by the reporting persons in the past sixty days and that the higher percentage figures reflect an increase in Allurion’s outstanding shares.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 11)

ALLURION TECHNOLOGIES, INC.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

Roderick Wong, M.D.
RTW Investments, LP, 40 10th Avenue, Floor 7
New York, NY, 10014
(646) 597-6980

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

02/26/2026

(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).

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

RTW Investments, LP

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 5,891,430.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 5,891,430.00

11

Aggregate amount beneficially owned by each reporting person

5,891,430.00

12

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

13

Percent of class represented by amount in Row (11)

39.4 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

RTW Master Fund, 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)

WC

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 3,138,798.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 3,138,798.00

11

Aggregate amount beneficially owned by each reporting person

3,138,798.00

12

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

13

Percent of class represented by amount in Row (11)

21.0 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

RTW Innovation Master Fund, 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)

WC

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 2,427,089.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,427,089.00

11

Aggregate amount beneficially owned by each reporting person

2,427,089.00

12

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

13

Percent of class represented by amount in Row (11)

16.2 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP Number(s):

1

Name of reporting person

Roderick Wong

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

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 5,891,430.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 5,891,430.00

11

Aggregate amount beneficially owned by each reporting person

5,891,430.00

12

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

13

Percent of class represented by amount in Row (11)

39.4 %

14

Type of Reporting Person (See Instructions)

HC, IN

SCHEDULE 13D

Item 1.	Security and Issuer
(a)	Title of Class of Securities: Common Stock, par value $0.0001 per share
(b)	Name of Issuer: ALLURION TECHNOLOGIES, INC.
(c)	Address of Issuer's Principal Executive Offices: 11 Huron Drive, Natick, MASSACHUSETTS , 01760.
Item 5.	Interest in Securities of the Issuer
(a)	Items 5(a)-(c) of the Schedule 13D are hereby amended and supplemented as follows: The aggregate percentage of Shares reported to be beneficially owned by the Reporting Persons is based upon the sum of (i) 12,279,181 Shares outstanding as of January 5, 2026 as reported in the Issuer's prospectus dated January 16, 2026 filed with the Securities and Exchange Commission (the "SEC") on January 20, 2026 and (ii) 2,659,565 Shares issued pursuant to an Inducement Offer to Exercise Common Stock Purchase Warrants dated February 24, 2026, which closed on February 26, 2026.
(b)	See rows (7) through (10) of the cover pages to this Schedule 13D/A for the number of shares of Common Stock 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)	No transactions with respect to the securities of the Issuer have been effected during the past sixty days by any Reporting Person. The percentage ownership reported in this Schedule 13D/A reflect an increase in the number of outstanding shares of the Issuer.

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:	Roderick Wong, M.D., Managing Partner
Date:	03/02/2026

RTW Master Fund, Ltd.

Signature:	/s/ Darshan Patel
Name/Title:	Darshan Patel, Director
Date:	03/02/2026

RTW Innovation Master Fund, Ltd.

Signature:	/s/ Darshan Patel
Name/Title:	Darshan Patel, Director
Date:	03/02/2026

Roderick Wong

Signature:	/s/ Roderick Wong, M.D.
Name/Title:	Roderick Wong, M.D.
Date:	03/02/2026

FAQ

How much of Allurion Technologies (ALUR) do RTW Investments and affiliates own?

RTW Investments, LP and related parties report beneficial ownership of 5,891,430 Allurion shares, or 39.4% of the common stock. This ownership is reported with shared voting and dispositive power, reflecting coordinated control over a large strategic position in the company.

What are the individual Allurion (ALUR) stakes of RTW’s Master Fund and Innovation Master Fund?

RTW Master Fund, Ltd holds 3,138,798 Allurion shares, representing 21.0% of the common stock. RTW Innovation Master Fund, Ltd holds 2,427,089 shares, representing 16.2%. Both funds report shared voting and shared dispositive power over their respective positions in Allurion.

Why did RTW file Amendment No. 11 to its Schedule 13D on Allurion (ALUR)?

The amendment updates RTW’s percentage ownership after an increase in Allurion’s outstanding shares. The filing explains that additional shares were issued under an Inducement Offer to Exercise Common Stock Purchase Warrants, and the revised 13D reflects the new ownership percentages based on that higher share count.

Did RTW or its funds trade Allurion Technologies (ALUR) shares in the last 60 days?

The filing states that no transactions in Allurion securities were effected by any reporting person during the past sixty days. The change in reported ownership results from an increase in Allurion’s total outstanding shares, not from recent buying or selling activity.

How were RTW’s Allurion (ALUR) ownership percentages calculated in this amendment?

The percentages are based on Allurion shares outstanding from a January 2026 prospectus plus additional shares issued in an inducement warrant exercise offer that closed February 26, 2026. RTW’s share counts are measured against this updated total share base.

What role does Roderick Wong play in the Allurion (ALUR) ownership reported?

Roderick Wong is listed as a reporting person with beneficial ownership of 5,891,430 shares, or 39.4% of Allurion’s common stock. These shares are reported with shared voting and dispositive power, aligning his interests with RTW-managed investment entities.