TNDM CFO updates insider holdings after RSU vesting, tax withholding

Rhea-AI Filing Summary

Tandem Diabetes Care Inc. (TNDM) reported an insider equity transaction by EVP & Chief Financial Officer Leigh Vosseller on 11/17/2025. The filing shows the exercise of restricted stock units (RSUs), converting 1,503 and 1,496 RSUs into common shares at an exercise price of $0.

To cover tax withholding on these vestings, the company withheld 538 and 536 shares at a price of $18.61 per share, with no open-market sales taking place. After these transactions, Vosseller directly owned 37,648 shares of common stock and an additional 25,580 shares indirectly through the Leigh A. Vosseller Trust.

The Form 4 also notes remaining RSU awards under the company’s 2023 Long-Term Incentive Plan, which continue to vest over time based on previously established schedules.

Insider Trade Summary

2,999 shares exercised/converted

Mixed 7 txns

Insider Vosseller Leigh

Role EVP & CHIEF FINANCIAL OFFICER

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Unit	1,503	$0.00	--
Exercise	Restricted Stock Unit	1,496	$0.00	--
Exercise	Common Stock	1,503	$0.00	--
Tax Withholding	Common Stock	538	$18.61	$10K
Exercise	Common Stock	1,496	$0.00	--
Tax Withholding	Common Stock	536	$18.61	$10K
holding	Common Stock	--	--	--

Holdings After Transaction: Restricted Stock Unit — 3,006 shares (Direct); Common Stock — 37,226 shares (Direct); Common Stock — 25,580 shares (Indirect, Leigh A. Vosseller Trust)

Footnotes (1)

1. 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 Leigh A. Vosseller Trust dated January 17, 2010, of which Leigh Vosseller is the 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^*

Vosseller Leigh

(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 FINANCIAL 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		M		1,503	A	$0	37,226	D
Common Stock	11/17/2025		F(1)		538	D	$18.61	36,688	D
Common Stock	11/17/2025		M		1,496	A	$0	38,184	D
Common Stock	11/17/2025		F(1)		536	D	$18.61	37,648	D
Common Stock								25,580	I	Leigh A. Vosseller Trust(2)

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(3)	(4)	11/17/2025		M			1,503	(5)	(5)	Common Stock	1,503	$0	3,006	D
Restricted Stock Unit(6)	(4)	11/17/2025		M			1,496	(7)	(7)	Common Stock	1,496	$0	8,973	D

Explanation of Responses:

1. 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.

2. The securities are held by the Leigh A. Vosseller Trust dated January 17, 2010, of which Leigh Vosseller is the Trustee.

3. 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).

4. 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.

5. 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.

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

7. 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 Leigh A. Vosseller	11/19/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did Tandem Diabetes Care (TNDM) report on this Form 4?

The Form 4 reports that EVP & CFO Leigh Vosseller exercised restricted stock units (RSUs) on 11/17/2025, converting 1,503 and 1,496 RSUs into common shares at an exercise price of $0.

Were any Tandem Diabetes Care (TNDM) shares sold in the open market?

No open-market sales occurred. The filing explains that 538 and 536 shares were withheld by the company solely to satisfy tax withholding requirements on the RSU vesting at a price of $18.61 per share.

How many Tandem Diabetes Care shares does the CFO own after the reported transactions?

Following the reported transactions, Leigh Vosseller beneficially owned 37,648 shares of common stock directly and 25,580 shares indirectly through the Leigh A. Vosseller Trust.

What is the relationship of the reporting person to Tandem Diabetes Care (TNDM)?

The reporting person, Leigh Vosseller, is an officer of Tandem Diabetes Care Inc., serving as EVP & Chief Financial Officer.

What do the RSU awards reported in this Form 4 represent?

Each RSU represents a contingent right to receive either one share of common stock or cash in lieu of a share, at the company’s discretion, under the 2023 Long-Term Incentive Plan.

How do the vesting schedules work for the reported Tandem Diabetes Care RSUs?

For the RSUs described, 33% of the total shares vest on a specified May 15 date, and the remaining shares vest in eight equal quarterly installments thereafter, according to the plan terms.