MASS · 908 Devices Inc.

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

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.00 to $9.07 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.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 20, 2025.

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.062 to $9.07 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.

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

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.61 to $8.95 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.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 20, 2025.

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.05 to $9.20 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 ranges set forth in footnotes (2), (3) and (4).

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become vested in substantially equal annual installments over the 3 years following June 25, 2024, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 20, 2025.

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.05 to $9.19 inclusive.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 20, 2025.

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.05 to $9.24 inclusive.

This is a weighted average price.

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 2,020,434 shares of Common Stock of the Issuer (the Shares) held by SSFQP, 577,077 Shares held by CAY, 266,802 Shares held by SSPE, 338,137 Shares held by TECH and 1,677,323 Shares held by TECH II.

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.

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

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.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 20, 2025.

The price reported is a weighted average price. These shares were sold in multiple transactions at prices ranging from $9.05 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 ranges set forth in footnotes (2), (3) and (4).

This is a weighted average price.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become fully vested on June 11, 2027 or the day prior to the 2027 Annual Meeting of the Stockholders of 908 Devices Inc., whichever occurs first, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following June 11, 2026, subject to the reporting person's continued service through the applicable vesting date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become fully vested on June 11, 2027 or the day prior to the 2027 Annual Meeting of the Stockholders of 908 Devices Inc., whichever occurs first, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following June 11, 2026, subject to the reporting person's continued service through the applicable vesting date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become fully vested on June 11, 2027 or the day prior to the 2027 Annual Meeting of the Stockholders of 908 Devices Inc., whichever occurs first, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become fully vested on June 11, 2027 or the day prior to the 2027 Annual Meeting of the Stockholders of 908 Devices Inc., whichever occurs first, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following June 11, 2026, subject to the reporting person's continued service through the applicable vesting date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become fully vested on June 11, 2027 or the day prior to the 2027 Annual Meeting of the Stockholders of 908 Devices Inc., whichever occurs first, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following June 11, 2026, subject to the reporting person's continued service through the applicable vesting date.

The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following June 11, 2026, subject to the reporting person's continued service through the applicable vesting date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become fully vested on June 11, 2027 or the day prior to the 2027 Annual Meeting of the Stockholders of 908 Devices Inc., whichever occurs first, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following June 11, 2026, subject to the reporting person's continued service through the applicable vesting date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs become fully vested on June 11, 2027 or the day prior to the 2027 Annual Meeting of the Stockholders of 908 Devices Inc., whichever occurs first, subject to the reporting person's continued service through the applicable vesting date, provided that, if the reporting person terminates their service for any reason, then a prorated number of RSUs will vest. The RSUs have no expiration date.

The shares underlying the option become vested and exercisable in substantially equal monthly installments over the 12 months following June 11, 2026, subject to the reporting person's continued service through the applicable vesting date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs became fully vested on June 10, 2026, the day prior to the 2026 Annual Meeting of the Stockholders of 908 Devices Inc. The RSUs have no expiration date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs became fully vested on June 10, 2026, the day prior to the 2026 Annual Meeting of the Stockholders of 908 Devices Inc. The RSUs have no expiration date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs became fully vested on June 10, 2026, the day prior to the 2026 Annual Meeting of the Stockholders of 908 Devices Inc. The RSUs have no expiration date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs became fully vested on June 10, 2026, the day prior to the 2026 Annual Meeting of the Stockholders of 908 Devices Inc. The RSUs have no expiration date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs became fully vested on June 10, 2026, the day prior to the 2026 Annual Meeting of the Stockholders of 908 Devices Inc. The RSUs have no expiration date.

Each Restricted Stock Unit ("RSU") represents a contingent right to receive one share of Common Stock, par value $0.001, when vested.

The RSUs became fully vested on June 10, 2026, the day prior to the 2026 Annual Meeting of the Stockholders of 908 Devices Inc. The RSUs have no expiration date.

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

This is a weighted average price.

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 2,025,616 shares of Common Stock of the Issuer (the Shares) held by SSFQP, 578,813 Shares held by CAY, 267,602 Shares held by SSPE, 338,137 Shares held by TECH and 1,677,323 Shares held by TECH II.

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.

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

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $8.61 to $8.86 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.

This is a weighted average price.

This transaction was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on June 2, 2025.

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

This is a weighted average price

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.

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 2,054,000 shares of Common Stock of the Issuer (the Shares) held by SSFQP, 588,327 Shares held by CAY, 271,986 Shares held by SSPE, 338,137 Shares held by TECH and 1,677,323 Shares held by TECH II.

This is a weighted average price

This is a weighted average price

This is a weighted average price.

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 2,179,495 shares of Common Stock of the Issuer (the Shares) held by SSFQP, 630,388 Shares held by CAY, 291,372 Shares held by SSPE, 338,137 Shares held by TECH and 1,677,323 Shares held by TECH II.

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.

This is a weighted average price.

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 2,182,852 shares of Common Stock of the Issuer (the Shares) held by SSFQP, 631,513 Shares held by CAY, 291,890 Shares held by SSPE, 338,137 Shares held by TECH and 1,677,323 Shares held by TECH II.

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.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.99 to $8.20 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.