Elizabeth A. Gasser - Nov 17, 2025 Form 4 Insider Report for TANDEM DIABETES CARE INC (TNDM)

Role: EVP, Chief Strategy Officer
Signature: /s/ Shannon M. Hansen, Attorney-in-Fact for Elizabeth A. Gasser
Stock symbol: TNDM
Transactions as of: Nov 17, 2025
Transactions value $: -$16,769
Form type: 4
Date filed: 11/19/2025, 04:06 PM
Previous filing: Aug 19, 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Gasser Elizabeth Anne	EVP, Chief Strategy Officer	12400 HIGH BLUFF DRIVE, SAN DIEGO	/s/ Shannon M. Hansen, Attorney-in-Fact for Elizabeth A. Gasser	2025-11-19	0001866283

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	TNDM	Common Stock	Award	$9.14K	+586	+48.55%	$15.59	1.79K	Nov 17, 2025	Direct	F1
transaction	TNDM	Common Stock	Options Exercise	$0	+1.5K	+83.83%	$0.00	3.3K	Nov 17, 2025	Direct
transaction	TNDM	Common Stock	Tax liability	-$15K	-805	-24.42%	$18.61	2.49K	Nov 17, 2025	Direct	F2
transaction	TNDM	Common Stock	Options Exercise	$0	+1.1K	+44%	$0.00	3.59K	Nov 17, 2025	Direct
transaction	TNDM	Common Stock	Tax liability	-$10.9K	-587	-16.36%	$18.61	3K	Nov 17, 2025	Direct	F2
holding	TNDM	Common Stock						22.9K	Nov 17, 2025	See Footnote	F3

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	-1.5K	-33.33%	$0.00	3.01K	Nov 17, 2025	Common Stock	1.5K		Direct	F4, F5, F6
transaction	TNDM	Restricted Stock Unit	Options Exercise	$0	-1.1K	-14.28%	$0.00	6.58K	Nov 17, 2025	Common Stock	1.1K		Direct	F5, F7, F8

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

Explanation of Responses:

Id	Content
F1	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 May 16, 2025, through November 17, 2025. This transaction is also exempt under Rule 16b-3(c).
F2	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.
F3	The securities are held by The Gasser Family Trust dated September 1, 2011, of which Elizabeth A. Gasser is a co-trustee.
F4	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	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	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.
F7	Awarded on May 23, 2024 pursuant to the 2023 Plan.
F8	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.