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  4. [Form 4] 908 Devices Inc. Insider Trading Activity

908 Devices (MASS) director Brown sells 17,800 shares in Rule 10b5-1 trades

Filing Impact
(Moderate)
Filing Sentiment
(Negative)
Form Type
4

Rhea-AI Filing Summary

908 Devices Inc. director Christopher D. Brown reported two open-market sales of common stock. On August 10, 2026, he sold 9,442 shares at a weighted average price of $9.03 per share, in multiple trades between $9.00 and $9.08. On August 11, 2026, he sold 8,358 shares at a weighted average price of $9.23, in trades between $9.06 and $9.36. The transactions, totaling 17,800 shares, were made pursuant to a Rule 10b5-1 trading plan adopted on November 24, 2025.

Positive

  • None.

Negative

  • None.
Insider Brown Christopher D.
Role Director
Sold 17,800 shs ($162K)
Type Security Shares Price Value
Sale Common Stock F1, F3 8,358 $9.23 $77K
Sale Common Stock F1, F2 9,442 $9.03 $85K
Holdings After Transaction: Common Stock — 805,559 shares (Direct)
Footnotes (3)
  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 $9.00 to $9.08 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.
  3. F3. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.06 to $9.36 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.
Shares sold 2026-08-10 9,442 shares at $9.03 per share Open-market or private sale of common stock on August 10, 2026
Shares sold 2026-08-11 8,358 shares at $9.23 per share Open-market or private sale of common stock on August 11, 2026
Total shares sold 17,800 shares Combined insider sales reported across both transactions
10b5-1 plan adoption date November 24, 2025 Date Christopher D. Brown adopted the Rule 10b5-1 trading plan
Rule 10b5-1 trading plan regulatory
"This transaction was made pursuant to a Rule 10b5-1 trading plan adopted"
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. These shares were sold"
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.
open market or private transaction financial
"Sale in open market or private transaction"

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

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Form 4 Insider Transactions: What Each Field Means →

FAQ

What insider transactions did 908 Devices (MASS) report for Christopher D. Brown?
Christopher D. Brown reported two sales totaling 17,800 shares of 908 Devices common stock on August 10 and 11, 2026, executed in open-market or private transactions at weighted average prices around $9.03 and $9.23 per share.

At what prices did Christopher D. Brown sell MASS shares?
He sold shares at weighted average prices of $9.03 on August 10, 2026 and $9.23 on August 11, 2026. The August 10 trades ranged from $9.00–$9.08, and the August 11 trades ranged from $9.06–$9.36 per share.

How many MASS shares did Christopher D. Brown sell on each date?
He sold 9,442 shares of 908 Devices common stock on August 10, 2026 and 8,358 shares on August 11, 2026. In total, the reported insider sales covered 17,800 shares across the two days.

Were the recent MASS insider sales under a Rule 10b5-1 plan?
Yes. The filing states the transactions were made pursuant to a Rule 10b5-1 trading plan adopted by Christopher D. Brown on November 24, 2025, indicating the sales were pre-arranged under that plan.

Does the Form 4 for MASS disclose the exact prices of each trade?
The Form 4 reports weighted average prices of $9.03 and $9.23 per share and notes the trades occurred in price ranges of $9.00–$9.08 and $9.06–$9.36. It offers to provide detailed per-trade prices upon request.
SEC Form 4
FORM 4UNITED 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)
XDirector10% Owner
Officer (give title below)Other (specify below)
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
08/10/2026		6. Individual or Joint/Group Filing (Check Applicable Line)
XForm 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)
CodeVAmount(A) or (D)Price
Common Stock08/10/2026S(1)9,442D$9.03(2)813,917D
Common Stock08/11/2026S(1)8,358D$9.23(3)805,559D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount 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 $9.00 to $9.08 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.
3. The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.06 to $9.36 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-Fact08/12/2026
** Signature of Reporting PersonDate
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)

Source: View Original Filing on SEC EDGAR