[SCHEDULE 13D/A] ALLURION TECHNOLOGIES, INC. SEC Filing

Rhea-AI Filing Summary

Allurion Technologies (ALUR): RTW files Amendment No. 9 to Schedule 13D, reporting beneficial ownership of 4,035,142 shares, or 43.6% of the common stock.

On November 5, 2025, the RTW funds converted $5.0 million principal amount of notes into 1,492,539 shares under an amended note purchase agreement. The ownership percentages are based on 7,762,681 shares outstanding as of August 8, 2025, plus the shares issued pursuant to the November 2025 conversion notice. RTW Investments, LP and Roderick Wong report shared voting and dispositive power over 4,035,142 shares.

By entity, RTW Master Fund, Ltd. reports 2,147,254 shares (23.2%), and RTW Innovation Master Fund, Ltd. reports 1,659,241 shares (17.9%). The notes include a 9.99% beneficial ownership conversion cap, while RTW’s warrants are subject to a 4.99% blocker that can be increased to 9.99% with 61 days’ prior notice.

Insights

Equity ownership & convertibles analyst

RTW discloses 43.6% stake after $5M note-to-equity conversion.

RTW reports control over 4,035,142 shares of Allurion, equal to 43.6% of the class. The change reflects a $5.0 million principal conversion into 1,492,539 shares on November 5, 2025, executed under an amended note purchase agreement.

Ownership math uses 7,762,681 shares outstanding as of August 8, 2025, plus the newly issued conversion shares. Beneficial ownership is constrained by a 9.99% note conversion cap. Warrants carry a 4.99% blocker, adjustable to 9.99% with 61 days notice.

Actual future share sales or further conversions depend on blocker settings and fund decisions. Subsequent filings may provide updates on conversions or changes to blockers.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 9)

ALLURION TECHNOLOGIES, INC.

(Name of Issuer)

Common Stock, par value $0.0001 per share

(Title of Class of Securities)

02008G201

(CUSIP Number)

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)

11/05/2025

(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 No. 02008G201

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 4,035,142.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,035,142.00

11

Aggregate amount beneficially owned by each reporting person

4,035,142.00

12

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

13

Percent of class represented by amount in Row (11)

43.6 %

14

Type of Reporting Person (See Instructions)

IA, PN

SCHEDULE 13D

CUSIP No. 02008G201

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 2,147,254.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 2,147,254.00

11

Aggregate amount beneficially owned by each reporting person

2,147,254.00

12

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

13

Percent of class represented by amount in Row (11)

23.2 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP No. 02008G201

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 1,659,241.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,659,241.00

11

Aggregate amount beneficially owned by each reporting person

1,659,241.00

12

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

13

Percent of class represented by amount in Row (11)

17.9 %

14

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13D

CUSIP No. 02008G201

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 4,035,142.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 4,035,142.00

11

Aggregate amount beneficially owned by each reporting person

4,035,142.00

12

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

13

Percent of class represented by amount in Row (11)

43.6 %

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 3.	Source and Amount of Funds or Other Consideration
	Item 3 of the Schedule 13D is hereby amended and supplemented as follows: The information set forth in Item 5(c) of this Amendment No. 9 is incorporated by reference herein to this Item 3.
Item 4.	Purpose of Transaction
	Item 4 of the Schedule 13D is hereby amended and supplemented as follows: The information set forth in Item 5(c) of this Amendment No. 9 is incorporated by reference herein to this Item 4.
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 (i) 7,762,681 Shares outstanding as of August 8, 2025, as disclosed in the Issuer's Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 19, 2025, and (ii) an additional 1,492,539 Shares issued pursuant to the November 2025 Conversion Notice (as defined in Item 6). The remaining principal amount of the Notes are subject to a beneficial ownership conversion limitation such that the RTW Funds cannot convert Notes to the extent it would result in the RTW Funds and their affiliates beneficially owning more than 9.99% of the Issuer's Shares, except as described in Item 6 hereof. The Warrants held by the RTW Funds are subject to a Blocker (as defined in Item 4 of Amendment No. 2 to the Schedule 13D), which is currently set at 4.99% and can be increased to 9.99% upon 61 days' prior notice by RTW.
(b)	See rows (7) through (10) of the cover pages to this Schedule 13D 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)	On November 5, 2025, the RTW Funds delivered the November 2025 Conversion Notice to acquire 1,492,539 Shares. Other than as reported herein, the Reporting Persons did not effect any transactions with respect to the Shares during the past sixty (60) days.
Item 6.	Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer
	Item 6 of the Statement is hereby amended and supplemented as follows: On November 5, 2025, pursuant to the terms of the Amended Note Purchase Agreement, the RTW Funds provided the Company with, and the Company accepted, a conversion notice (the "November 2025 Conversion Notice"), pursuant to which $5.0 million aggregate principal amount of the Notes was converted into an aggregate of 1,492,539 Shares.

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:	11/07/2025

RTW Master Fund, Ltd.

Signature:	/s/ Roderick Wong, M.D.
Name/Title:	Roderick Wong, M.D., Director
Date:	11/07/2025

RTW Innovation Master Fund, Ltd.

Signature:	/s/ Roderick Wong, M.D.
Name/Title:	Roderick Wong, M.D., Director
Date:	11/07/2025

Roderick Wong

Signature:	/s/ Roderick Wong, M.D.
Name/Title:	Roderick Wong, M.D.
Date:	11/07/2025

FAQ

What stake did RTW disclose in Allurion (ALUR)?

RTW reported beneficial ownership of 4,035,142 shares, representing 43.6% of Allurion’s common stock.

What transaction impacted RTW’s ownership in ALUR?

On November 5, 2025, RTW converted $5.0 million of notes into 1,492,539 shares.

What share count did RTW use to calculate its percentage ownership in ALUR?

The calculation used 7,762,681 shares outstanding as of August 8, 2025, plus the 1,492,539 newly issued conversion shares.

How much does RTW Master Fund, Ltd. own of ALUR?

RTW Master Fund, Ltd. reports 2,147,254 shares, or 23.2% of the class.

How much does RTW Innovation Master Fund, Ltd. own of ALUR?

RTW Innovation Master Fund, Ltd. reports 1,659,241 shares, or 17.9%.

Are there limits on RTW’s conversions or exercises?

Yes. Notes have a 9.99% beneficial ownership conversion cap; warrants have a 4.99% blocker, increaseable to 9.99% with 61 days’ notice.