[Form 4] TANDEM DIABETES CARE INC Insider Trading Activity

Rhea-AI Filing Summary

Tandem Diabetes Care (TNDM) Chief Technology Officer Rick A. Carpenter reported several equity transactions involving company stock. He voluntarily disclosed acquiring 339 shares of common stock at $15.59 per share through the company’s Employee Stock Purchase Plan for the period from May 16, 2025 through November 17, 2025.

On the same date, 1,437 and 897 restricted stock units (RSUs) were converted into common shares at a $0 exercise price under the 2023 Long-Term Incentive Plan. To cover taxes on these RSU vestings, the company withheld 730 and 456 shares at a price of $18.61 per share, with no shares sold on the market. After these transactions, Carpenter directly beneficially owned 24,053 shares of Tandem Diabetes Care common stock.

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

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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^*

Carpenter Rick

(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)
	Chief Technology 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		339	A(1)	$15.59	22,905	D
Common Stock	11/17/2025		M		1,437	A	$0	24,342	D
Common Stock	11/17/2025		F(2)		730	D	$18.61	23,612	D
Common Stock	11/17/2025		M		897	A	$0	24,509	D
Common Stock	11/17/2025		F(2)		456	D	$18.61	24,053	D

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			1,437	(5)	(5)	Common Stock	1,437	$0	2,874	D
Restricted Stock Unit(6)	(4)	11/17/2025		M			897	(7)	(7)	Common Stock	897	$0	5,384	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. 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 Rick A. Carpenter	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 did Tandem Diabetes Care (TNDM) disclose in this Form 4 filing?

The filing reports Rick A. Carpenter, Chief Technology Officer of Tandem Diabetes Care, acquiring shares through the Employee Stock Purchase Plan and the vesting of restricted stock units, along with related tax withholding transactions, all dated November 17, 2025.

How many Tandem Diabetes Care (TNDM) shares did the CTO buy through the ESPP?

Rick A. Carpenter acquired 339 shares of common stock at a price of $15.59 per share under the Tandem Diabetes Care Inc. Amended and Restated 2013 Employee Stock Purchase Plan for the period from May 16, 2025 through November 17, 2025.

What RSU-related transactions were reported for Tandem Diabetes Care (TNDM)?

The CTO reported the conversion of 1,437 RSUs and 897 RSUs into common shares at a $0 exercise price under the 2023 Long-Term Incentive Plan, with each RSU representing a contingent right to one share of common stock or cash in lieu.

Were any Tandem Diabetes Care (TNDM) shares sold in the market in this Form 4?

No market sales were reported. Instead, the company withheld 730 shares and 456 shares of common stock at $18.61 per share to satisfy tax withholding obligations arising from RSU vesting, and the filing explicitly notes that no shares were sold.

What is the CTO’s total beneficial ownership of Tandem Diabetes Care (TNDM) stock after these transactions?

Following the reported ESPP purchase, RSU conversions, and share withholding for taxes, Rick A. Carpenter directly beneficially owned 24,053 shares of Tandem Diabetes Care common stock.

Which incentive plans are referenced in this Tandem Diabetes Care (TNDM) Form 4?

The filing references the Tandem Diabetes Care Inc. Amended and Restated 2013 Employee Stock Purchase Plan and the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, under which the ESPP purchase and RSU awards and vesting occurred.