908 Devices director Brown sells 30,000 shares

The director's sale was made under a Rule 10b5-1 trading plan adopted on November 24, 2025.

Available on EDGAR 11/06/2026 - 04:30 PM EST Accepted by SEC EDGAR 11/06/2026 - 04:30 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

908 Devices Inc. director Christopher D. Brown sold 30,000 common shares on November 4, 2026, at a weighted average price of $10.95 per share. The shares were sold in multiple transactions priced from $10.60 to $11.09, inclusive, under a Rule 10b5-1 trading plan adopted on November 24, 2025. He directly held 775,559 shares after the sale.

Insider Trade Summary 10b5-1

Net Seller: 30,000 shares

Net Sell 1 txn

Insider Brown Christopher D.

Role Director

Sold 30,000 shs ($329K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	30,000	$10.95	$329K

Holdings After Transaction: Common Stock — 775,559 shares (Direct)

Footnotes (2)

1. F1. This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 24, 2025.
2. F2. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.60 to $11.09 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

Key Figures

Shares sold: 30,000 shares Weighted average price: $10.95 per share Transaction price range: $10.60–$11.09 per share +1 more

4 metrics

Shares sold 30,000 shares November 4, 2026

Weighted average price $10.95 per share Sale on November 4, 2026

Transaction price range $10.60–$11.09 per share Inclusive range across multiple transactions

Shares held after sale 775,559 shares Direct holdings following the transaction

Key Terms

Rule 10b5-1 trading plan, weighted average price, Reporting Person

3 terms

Rule 10b5-1 trading plan regulatory

"made pursuant to a Rule 10b5-1 trading plan"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

weighted average price financial

"The price reported 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.

Reporting Person regulatory

"adopted by the Reporting Person on November 24, 2025"

FAQ

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

How many MASS shares did director Christopher D. Brown sell, and at what price?

Christopher D. Brown sold 30,000 shares on November 4, 2026, at a weighted average price of $10.95 per share. The transactions were priced from $10.60 to $11.09 per share, inclusive.

Was Christopher D. Brown's MASS share sale made under a trading plan?

Yes. The sale was made under a Rule 10b5-1 trading plan adopted on November 24, 2025.

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

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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).

X

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^*

Brown Christopher D.

(Last) (First) (Middle)

C/O 908 DEVICES INC.

44 3RD AVENUE

(Street)

BURLINGTON MASSACHUSETTS 01803

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
11/04/2026

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	11/04/2026		S(1)		30,000	D	$10.95(2)	775,559	D

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 transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 24, 2025.

2. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.60 to $11.09 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

	/s/ Mark S. Levine, Attorney-in-Fact	11/06/2026
	** 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)