908 Devices 10% owner sells 24,000 shares

The reported weighted-average sale prices were $11.25 and $11.3594 per share; post-transaction holdings were reported as 4,755,773 and 4,754,773 shares.

Rhea-AI Filing Summary

AWM Investment Company, Inc., a ten-percent owner of 908 Devices Inc., reported two indirect sales of Common Stock through limited partnerships: 1,000 shares on September 23, 2026, at a weighted-average price of $11.25 per share, and 24,000 shares on September 24, 2026, at a weighted-average price of $11.3594 per share. Reported holdings following the September 23 sale were 4,755,773 shares; following the September 24 sale, they were 4,754,773 shares.

Insider Trade Summary

Net Seller: 25,000 shares

Net Sell 2 txns

Insider AWM Investment Company, Inc.

Role 10% Owner

Sold 25,000 shs ($284K)

Type	Security	Shares	Price	Value
Sale	Common Stock F2, F3, F1	24,000	$11.3594	$273K
Sale	Common Stock F1	1,000	$11.25	$11K

Holdings After Transaction: Common Stock — 4,755,773 shares (Indirect, By Limited Partnershp); Common Stock — 4,754,773 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, 216,802 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

Shares sold: 1,000 shares Weighted-average sale price: $11.25 per share Reported holdings after sale: 4,755,773 shares +3 more

6 metrics

Shares sold 1,000 shares September 23, 2026

Weighted-average sale price $11.25 per share September 23, 2026

Reported holdings after sale 4,755,773 shares Following the September 23, 2026 sale

Shares sold 24,000 shares September 24, 2026

Weighted-average sale price $11.3594 per share September 24, 2026

Reported holdings after sale 4,754,773 shares Following the September 24, 2026 sale

Key Terms

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

4 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 regulatory

"except to the extent of its pecuniary interest therein"

beneficial ownership regulatory

"disclaims beneficial ownership of the Shares"

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.

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 prices?

AWM Investment Company, Inc. reported indirect sales of 1,000 shares on September 23, 2026, at a weighted-average price of $11.25 per share and 24,000 shares on September 24, 2026, at a weighted-average price of $11.3594 per share.

Were the MASS sales made under a Rule 10b5-1 plan?

The report states that no Rule 10b5-1 plan applied to these transactions.

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

Form 4 Insider Transactions: What Each Field Means →

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Available on EDGAR 09/25/2026 - 04:34 PM Accepted by SEC EDGAR 09/25/2026 - 04:19 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)
09/23/2026

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	09/23/2026		S		1,000	D	$11.25(1)	4,755,773	I	By Limited Partnershp
Common Stock	09/24/2026		S		24,000(2)(3)	D	$11.3594(1)	4,754,773(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, 216,802 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	09/25/2026
	** 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)