[Form 4] TANDEM DIABETES CARE INC Insider Trading Activity

Rhea-AI Filing Summary

Tandem Diabetes Care (TNDM) executive vice president and chief strategy officer Elizabeth A. Gasser reported several equity transactions in the company’s stock. She voluntarily disclosed acquiring 586 shares of common stock at $15.59 through the company’s Employee Stock Purchase Plan for the May 16, 2025 to November 17, 2025 purchase period.

On the same date, 1,503 and 1,096 shares of common stock were delivered upon the vesting of previously granted restricted stock units, at an exercise price of $0. To cover tax withholding on these RSU vestings, the company withheld 805 and 587 shares at a price of $18.61 per share; no shares were sold into the market.

Following these transactions, Gasser directly beneficially owns 3,000 shares of Tandem Diabetes Care common stock and indirectly beneficially owns 22,949 shares through The Gasser Family Trust dated September 1, 2011, where she serves as co-trustee. The RSUs were granted under the company’s 2023 Long-Term Incentive Plan and vest over multi-year schedules.

Insider Trade Summary

2,599 shares exercised/converted

Mixed 8 txns

Insider Gasser Elizabeth Anne

Role EVP, Chief Strategy Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Unit	1,503	$0.00	--
Exercise	Restricted Stock Unit	1,096	$0.00	--
Grant/Award	Common Stock	586	$15.59	$9K
Exercise	Common Stock	1,503	$0.00	--
Tax Withholding	Common Stock	805	$18.61	$15K
Exercise	Common Stock	1,096	$0.00	--
Tax Withholding	Common Stock	587	$18.61	$11K
holding	Common Stock	--	--	--

Holdings After Transaction: Restricted Stock Unit — 3,006 shares (Direct); Common Stock — 1,793 shares (Direct); Common Stock — 22,949 shares (Indirect, See Footnote)

Footnotes (1)

1. 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). 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. The securities are held by The Gasser Family Trust dated September 1, 2011, of which Elizabeth A. Gasser is a co-trustee. 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). 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. 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. Awarded on May 23, 2024 pursuant to the 2023 Plan. 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.

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED 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).

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^*

Gasser Elizabeth Anne

(Last) (First) (Middle)

12400 HIGH BLUFF DRIVE

(Street)

SAN DIEGO CA 92130

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
TANDEM DIABETES CARE INC [ TNDM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP, Chief Strategy Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/17/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	11/17/2025		A		586	A(1)	$15.59	1,793	D
Common Stock	11/17/2025		M		1,503	A	$0	3,296	D
Common Stock	11/17/2025		F(2)		805	D	$18.61	2,491	D
Common Stock	11/17/2025		M		1,096	A	$0	3,587	D
Common Stock	11/17/2025		F(2)		587	D	$18.61	3,000	D
Common Stock								22,949	I	See Footnote(3)

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Unit(4)	(5)	11/17/2025		M			1,503	(6)	(6)	Common Stock	1,503	$0	3,006	D
Restricted Stock Unit(7)	(5)	11/17/2025		M			1,096	(8)	(8)	Common Stock	1,096	$0	6,581	D

Explanation of Responses:

1. 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).

2. 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.

3. The securities are held by The Gasser Family Trust dated September 1, 2011, of which Elizabeth A. Gasser is a co-trustee.

4. 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).

5. 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.

6. 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.

7. Awarded on May 23, 2024 pursuant to the 2023 Plan.

8. 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.

Remarks:

	/s/ Shannon M. Hansen, Attorney-in-Fact for Elizabeth A. Gasser	11/19/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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