Vosseller Leigh

SEC source: 0001438133-26-000132 · wk-form4_1787084926.xml · derivative · entry 7

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 18,368

Underlying: Common Stock · 2,624 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · security: Awarded on May 30, 2025 pursuant to the 2023 Plan.

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F7 · derivative.exercise_date: One-third of the RSUs granted on May 30, 2025 vested on May 15, 2026, with the remaining RSUs vesting in eight (8) equal quarterly installments thereafter, subject to the terms of the 2023 Plan.

F7 · derivative.expiration_date: One-third of the RSUs granted on May 30, 2025 vested on May 15, 2026, with the remaining RSUs vesting in eight (8) equal quarterly installments thereafter, subject to the terms of the 2023 Plan.

SEC source: 0001438133-26-000132 · wk-form4_1787084926.xml · derivative · entry 6

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 4,486

Underlying: Common Stock · 1,496 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · security: Awarded on May 23, 2024 pursuant to the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F5 · derivative.exercise_date: One-third of the RSUs granted on May 23, 2024 vested on May 15, 2025, with the remaining RSUs vesting in eight (8) equal quarterly installments thereafter, subject to the terms of the 2023 Plan.

F5 · derivative.expiration_date: One-third of the RSUs granted on May 23, 2024 vested on May 15, 2025, with the remaining RSUs vesting in eight (8) equal quarterly installments thereafter, subject to the terms of the 2023 Plan.

SEC source: 0001438133-26-000132 · wk-form4_1787084926.xml · nonDerivative · entry 4

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 52,040

F1 · kind: Shares withheld by the Issuer to satisfy tax withholding requirements upon the vesting of restricted stock units (RSUs). No shares were sold.

SEC source: 0001438133-26-000132 · wk-form4_1787084926.xml · nonDerivative · entry 3

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 52,982

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-26-000132 · wk-form4_1787084926.xml · nonDerivative · entry 2

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 50,358

F1 · kind: Shares withheld by the Issuer to satisfy tax withholding requirements upon the vesting of restricted stock units (RSUs). No shares were sold.

SEC source: 0001438133-26-000132 · wk-form4_1787084926.xml · nonDerivative · entry 1

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 50,895

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-26-000111 · wk-form4_1780431664.xml · derivative · entry 1

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 62,657

Underlying: Common Stock · 62,657 shares

Expires not disclosed

F1 · derivative.exercise_price: Each restricted stock unit (RSU) represents a contingent right to receive either one share of the Issuer's common stock or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the Tandem Diabetes Care, Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F2 · derivative.exercise_date: One-third of such RSUs shall vest on 5/29/2027, and the remaining RSUs shall vest in eight (8) equal quarterly installments on the 15th of the month thereafter subject to the terms of the 2023 Plan.

F2 · derivative.expiration_date: One-third of such RSUs shall vest on 5/29/2027, and the remaining RSUs shall vest in eight (8) equal quarterly installments on the 15th of the month thereafter subject to the terms of the 2023 Plan.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · derivative · entry 11

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 20,992

Underlying: Common Stock · 10,496 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F9 · security: Awarded on May 30, 2025 pursuant to the 2023 Plan.

F5 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F10 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2026, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F10 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2026, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · derivative · entry 10

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 5,982

Underlying: Common Stock · 1,496 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · security: Awarded on May 23, 2024 pursuant to the 2023 Plan.

F5 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F8 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F8 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · derivative · entry 9

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 1,503 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · security: Awarded on May 25, 2023 pursuant to the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F5 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F6 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F6 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · nonDerivative · entry 7

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 49,399

F2 · kind: The reporting person is voluntarily reporting the acquisition of shares of common stock pursuant to the Tandem Diabetes Care, Inc. Amended and Restated 2013 Employee Stock Purchase Plan (ESPP), for the ESPP purchase period of November 18, 2025, through May 15, 2026. This transaction is also exempt under Rule 16b-3(c).

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · nonDerivative · entry 6

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 48,063

F1 · kind: Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · nonDerivative · entry 5

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 51,829

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · nonDerivative · entry 4

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 41,333

F1 · kind: Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · nonDerivative · entry 3

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 41,870

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · nonDerivative · entry 2

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,374

F1 · kind: Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-26-000056 · wk-form4_1779221027.xml · nonDerivative · entry 1

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,914

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-26-000013 · wk-form4_1771536848.xml · derivative · entry 7

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 7,478

Underlying: Common Stock · 1,495 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · security: Awarded on May 23, 2024 pursuant to the 2023 Plan.

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F7 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F7 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-26-000013 · wk-form4_1771536848.xml · derivative · entry 6

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 1,503

Underlying: Common Stock · 1,503 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · security: Awarded on May 25, 2023 pursuant to the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F5 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F5 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-26-000013 · wk-form4_1771536848.xml · nonDerivative · entry 4

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 39,411

F1 · shares: Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-26-000013 · wk-form4_1771536848.xml · nonDerivative · entry 3

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 40,027

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-26-000013 · wk-form4_1771536848.xml · nonDerivative · entry 2

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 38,532

F1 · shares: Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-26-000013 · wk-form4_1771536848.xml · nonDerivative · entry 1

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 39,151

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-25-000208 · wk-form4_1763586386.xml · derivative · entry 7

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,973

Underlying: Common Stock · 1,496 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · security: Awarded on May 23, 2024 pursuant to the 2023 Plan.

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F7 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F7 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-25-000208 · wk-form4_1763586386.xml · derivative · entry 6

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 3,006

Underlying: Common Stock · 1,503 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · security: Awarded on May 25, 2023 pursuant to the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F5 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F5 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-25-000208 · wk-form4_1763586386.xml · nonDerivative · entry 4

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 37,648

F1 · kind: Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-25-000208 · wk-form4_1763586386.xml · nonDerivative · entry 3

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 38,184

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-25-000208 · wk-form4_1763586386.xml · nonDerivative · entry 2

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 36,688

F1 · kind: Shares withheld by Tandem Diabetes Care Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-25-000208 · wk-form4_1763586386.xml · nonDerivative · entry 1

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 37,226

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-25-040842 · wk-form4_1755641658.xml · derivative · entry 7

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 10,469

Underlying: Common Stock · 1,495 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · security: Awarded on May 23, 2024 pursuant to the 2023 Plan.

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F7 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F7 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001628280-25-040842 · wk-form4_1755641658.xml · derivative · entry 6

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 4,509

Underlying: Common Stock · 1,503 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · security: Awarded on May 25, 2023 pursuant to the Tandem Diabetes Care, Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F4 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F5 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F5 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001628280-25-040842 · wk-form4_1755641658.xml · nonDerivative · entry 4

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 35,723

F1 · kind: Shares withheld by Tandem Diabetes Care, Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001628280-25-040842 · wk-form4_1755641658.xml · nonDerivative · entry 3

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 36,258

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001628280-25-040842 · wk-form4_1755641658.xml · nonDerivative · entry 2

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 34,763

F1 · kind: Shares withheld by Tandem Diabetes Care, Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001628280-25-040842 · wk-form4_1755641658.xml · nonDerivative · entry 1

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 35,301

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-25-000163 · wk-form4_1754947125.xml · nonDerivative · entry 1

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Indirect · Leigh A. Vosseller Trust

Disclosed balance after: 25,580

F1 · price: This transaction was executed in multiple trades at prices ranging from $10.86 to $10.90 per share. The reported price reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

F2 · ownership.nature: The securities are held by the Leigh A. Vosseller Trust dated January 17, 2010, of which Leigh Vosseller is the Trustee.

SEC source: 0001438133-25-000135 · wk-form4_1749158816.xml · derivative · entry 4

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,488

Underlying: Common Stock · 31,488 shares

Expires not disclosed

F2 · security: Awarded on May 30, 2025 pursuant to the Tandem Diabetes Care, Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F4 · derivative.exercise_price: Each restricted stock unit (RSU) represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F5 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2026, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F5 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2026, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-25-000135 · wk-form4_1749158816.xml · derivative · entry 3

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 31,486

Underlying: Common Stock · 31,486 shares

Expires not disclosed

F2 · security: Awarded on May 30, 2025 pursuant to the Tandem Diabetes Care, Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F3 · derivative.exercise_price: Each performance stock unit (PSU) represents a contingent right to receive one share of Tandem Diabetes Care, Inc. (the Company) common stock based upon the achievement of certain pre-defined performance metrics as of December 31, 2027 (the Measurement Date). The number of shares issued may range from 0% to 200% of the amount specified above, based upon (i) Company's actual performance relative to the pre-defined performance metrics, and (ii) subject to the awardee's continuing service through the Measurement Date. If minimum performance metrics are not met, no PSUs will vest.

F3 · derivative.exercise_date: Each performance stock unit (PSU) represents a contingent right to receive one share of Tandem Diabetes Care, Inc. (the Company) common stock based upon the achievement of certain pre-defined performance metrics as of December 31, 2027 (the Measurement Date). The number of shares issued may range from 0% to 200% of the amount specified above, based upon (i) Company's actual performance relative to the pre-defined performance metrics, and (ii) subject to the awardee's continuing service through the Measurement Date. If minimum performance metrics are not met, no PSUs will vest.

F3 · derivative.expiration_date: Each performance stock unit (PSU) represents a contingent right to receive one share of Tandem Diabetes Care, Inc. (the Company) common stock based upon the achievement of certain pre-defined performance metrics as of December 31, 2027 (the Measurement Date). The number of shares issued may range from 0% to 200% of the amount specified above, based upon (i) Company's actual performance relative to the pre-defined performance metrics, and (ii) subject to the awardee's continuing service through the Measurement Date. If minimum performance metrics are not met, no PSUs will vest.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · derivative · entry 14

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 11,964

Underlying: Common Stock · 5,982 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F12 · security: Awarded on May 23, 2024 pursuant to the 2023 Plan.

F10 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F13 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F13 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · derivative · entry 13

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 6,012

Underlying: Common Stock · 1,503 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F9 · security: Awarded on May 25, 2023 pursuant to the Tandem Diabetes Care, Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

F10 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2023 Plan.

F11 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F11 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2024, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · derivative · entry 12

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 474 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · security: Awarded on May 25, 2022 pursuant to the 2013 Plan.

F5 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2013 Plan.

F8 · derivative.exercise_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2023, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

F8 · derivative.expiration_date: RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2023, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · derivative · entry 11

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 162 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · security: Awarded on May 18, 2021 pursuant to the Tandem Diabetes Care, Inc. 2013 Stock Incentive Plan, as amended, and the agreements related thereto (the 2013 Plan).

F5 · derivative.exercise_price: Each RSU represents a contingent right to receive either one share of common stock of the Issuer or cash in lieu thereof, at the Issuer's discretion, in accordance with the terms of the 2013 Plan.

F6 · derivative.exercise_date: RSU vest as to twenty-five percent (25%) of the total number of shares subject to the RSU on 5/15/2022, and the remaining shares shall vest in twelve (12) equal quarterly installments thereafter.

F6 · derivative.expiration_date: RSU vest as to twenty-five percent (25%) of the total number of shares subject to the RSU on 5/15/2022, and the remaining shares shall vest in twelve (12) equal quarterly installments thereafter.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 9

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,798

F2 · kind: Shares withheld by Tandem Diabetes Care, Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 8

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 35,939

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 7

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 29,957

F2 · kind: Shares withheld by Tandem Diabetes Care, Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 6

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 30,495

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 5

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 28,992

F2 · kind: Shares withheld by Tandem Diabetes Care, Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 4

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 29,162

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 3

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 28,688

F2 · kind: Shares withheld by Tandem Diabetes Care, Inc. (the Company) to satisfy tax withholding requirements on vesting of restricted stock units (RSU). No shares were sold.

SEC source: 0001438133-25-000083 · wk-form4_1747692327.xml · nonDerivative · entry 2

Vosseller Leigh · CIK 0001726322 · EVP & CHIEF FINANCIAL OFFICER

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 28,746

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.