908 Devices 10% owner AWM sells 18,000 shares

AWM disclaims beneficial ownership of the shares except to the extent of its pecuniary interest.

Rhea-AI Filing Summary

908 Devices Inc. (MASS) ten-percent owner AWM Investment Company, Inc. reported an indirect sale of 18,000 common shares held by a limited partnership on September 29, 2026, at a weighted average price of $11.5179 per share. The reported position following the sale was 4,736,773 shares. AWM is identified as investment adviser to several funds, with sole voting and investment power over fund-held shares. David M. Greenhouse and Adam C. Stettner are identified as AWM's controlling principals.

Insider Trade Summary

Net Seller: 18,000 shares

Net Sell 1 txn

Insider AWM Investment Company, Inc.

Role 10% Owner

Sold 18,000 shs ($207K)

Type	Security	Shares	Price	Value
Sale	Common Stock F2, F3, F1	18,000	$11.5179	$207K

Holdings After Transaction: Common Stock — 4,736,773 shares (Indirect, By Limited Partnership)

Footnotes (3)

1. F1. This is a weighted average price.
2. F2. AWM Investment Company, Inc., a Delaware Corporation (AWM), is the investment adviser to Special Situations Fund III QP, L.P. (SSFQP), Special Situations Cayman Fund, L.P. (CAY), Special Situations Private Equity Fund, L.P. (SSPE), Special Situations Technology Fund, L.P. (TECH) and Special Situations Technology Fund II, L.P. (TECH II and together with SSFQP, CAY, SSPE and TECH, the Funds). As the investment adviser to the Funds, AWM holds sole voting and investment power over 1,962,485 shares of Common Stock of the Issuer (the Shares) held by SSFQP, 560,026 Shares held by CAY, 198,802 Shares held by SSPE, 338,137 Shares held by TECH and 1,677,323 Shares held by TECH II.
3. F3. David M. Greenhouse (Greenhouse) and Adam C. Stettner (Stettner) are the controlling principals of AWM. The reporting person disclaims beneficial ownership of the Shares, except to the extent of its pecuniary interest therein. This report shall not be deemed an admission that the reporting person is the beneficial owner of the securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

Key Figures

Common shares sold: 18,000 shares Weighted average sale price: $11.5179 per share Shares following transaction: 4,736,773 shares

3 metrics

Common shares sold 18,000 shares September 29, 2026

Weighted average sale price $11.5179 per share September 29, 2026

Shares following transaction 4,736,773 shares Reported following the sale

Key Terms

weighted average price, sole voting and investment power, pecuniary interest

3 terms

weighted average price financial

"This is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

sole voting and investment power regulatory

"AWM holds sole voting and investment power over"

pecuniary interest financial

"except to the extent of its pecuniary interest therein"

FAQ

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

How many MASS shares did AWM Investment Company, Inc. sell, and at what price?

AWM Investment Company, Inc. reported an indirect sale of 18,000 common shares on September 29, 2026, at a weighted average price of $11.5179 per share. The reported position following the transaction was 4,736,773 shares. No Rule 10b5-1 plan is reported.

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

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Available on EDGAR 10/01/2026 - 05:02 PM Accepted by SEC EDGAR 10/01/2026 - 05:02 PM Learn about SEC filing dates

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

AWM Investment Company, Inc.

(Last) (First) (Middle)

527 MADISON AVENUE

SUITE 2600

(Street)

NEW YORK NEW YORK 10022

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
908 Devices Inc. [ MASS ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/29/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	09/29/2026		S		18,000(2)(3)	D	$11.5179(1)	4,736,773(2)(3)	I(2)(3)	By Limited Partnership(2)(3)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. This is a weighted average price.

2. AWM Investment Company, Inc., a Delaware Corporation (AWM), is the investment adviser to Special Situations Fund III QP, L.P. (SSFQP), Special Situations Cayman Fund, L.P. (CAY), Special Situations Private Equity Fund, L.P. (SSPE), Special Situations Technology Fund, L.P. (TECH) and Special Situations Technology Fund II, L.P. (TECH II and together with SSFQP, CAY, SSPE and TECH, the Funds). As the investment adviser to the Funds, AWM holds sole voting and investment power over 1,962,485 shares of Common Stock of the Issuer (the Shares) held by SSFQP, 560,026 Shares held by CAY, 198,802 Shares held by SSPE, 338,137 Shares held by TECH and 1,677,323 Shares held by TECH II.

3. David M. Greenhouse (Greenhouse) and Adam C. Stettner (Stettner) are the controlling principals of AWM. The reporting person disclaims beneficial ownership of the Shares, except to the extent of its pecuniary interest therein. This report shall not be deemed an admission that the reporting person is the beneficial owner of the securities reported herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended, or for any other purpose.

	Adam Stettner	10/01/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)