Leigh A. Vosseller - 17 Nov 2025 Form 4 Insider Report for TANDEM DIABETES CARE INC (TNDM)

Role: EVP & CHIEF FINANCIAL OFFICER
Signature: /s/ Shannon M. Hansen, Attorney-in-Fact for Leigh A. Vosseller
Issuer symbol: TNDM
Transactions as of: 17 Nov 2025
Net transactions value: -$19,987
Form type: 4
Filing time: 19 Nov 2025, 16:06:29 UTC
Previous filing: 19 Aug 2025
Next filing: 19 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Vosseller Leigh	EVP & CHIEF FINANCIAL OFFICER	12400 HIGH BLUFF DRIVE, SAN DIEGO	/s/ Shannon M. Hansen, Attorney-in-Fact for Leigh A. Vosseller	19 Nov 2025	0001726322

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	TNDM	Common Stock	Options Exercise	$0	+1,503	+4.2%	$0.000000	37,226	17 Nov 2025	Direct
transaction	TNDM	Common Stock	Tax liability	$10,012	-538	-1.4%	$18.61	36,688	17 Nov 2025	Direct	F1
transaction	TNDM	Common Stock	Options Exercise	$0	+1,496	+4.1%	$0.000000	38,184	17 Nov 2025	Direct
transaction	TNDM	Common Stock	Tax liability	$9,975	-536	-1.4%	$18.61	37,648	17 Nov 2025	Direct	F1
holding	TNDM	Common Stock						25,580	17 Nov 2025	Leigh A. Vosseller Trust	F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	TNDM	Restricted Stock Unit	Options Exercise	$0	-1,503	-33%	$0.000000	3,006	17 Nov 2025	Common Stock	1,503		Direct	F3, F4, F5
transaction	TNDM	Restricted Stock Unit	Options Exercise	$0	-1,496	-14%	$0.000000	8,973	17 Nov 2025	Common Stock	1,496		Direct	F4, F6, F7

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	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.
F2	The securities are held by the Leigh A. Vosseller Trust dated January 17, 2010, of which Leigh Vosseller is the Trustee.
F3	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	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	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	Awarded on May 23, 2024 pursuant to the 2023 Plan.
F7	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.