[Form 4] Tandem Diabetes Care, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Rick A. Carpenter, Chief Technology Officer of Tandem Diabetes Care, Inc. (TNDM), reported multiple equity transactions on 08/15/2025. Two grants of restricted stock units (RSUs) vested, resulting in 1,437 and 898 shares being issued at $0 as part of long-term incentive awards. To satisfy tax withholding on vesting, the company withheld 730 and 457 shares; the withheld shares were not sold. After the reported transactions, the filing shows common stock beneficial ownership balances changing between 21,926 and 22,824 shares and derivative (RSU) balances of 4,311 and 6,281 shares as reported in the table. The RSUs were awarded under the 2023 Long-Term Incentive Plan and vest on a 33% initial schedule with subsequent quarterly installments.

Positive

• RSU vesting increased insider ownership with 1,437 and 898 shares issued at $0 as compensation-related vesting
• Clear disclosure that withheld shares were used solely for tax withholding and that no shares were sold

Negative

• Tax withholding reduced issued shares with 730 and 457 shares withheld, lowering the net increase in outstanding shares to the reporting person

Insights

Financial Analyst

TL;DR: Insider RSU vesting increased holdings modestly while shares were withheld for taxes; no open-market sales reported.

Carpenter received 2,335 shares through RSU vesting and had 1,187 shares withheld for tax withholding, per the filing. The transactions are compensation-related (vested RSUs) rather than discretionary sales, and the filing explicitly states no shares were sold. For investors this is a routine compensation event that modestly increases insider equity exposure; it does not reflect active cash-generation selling by the insider.

Corporate Governance Expert

TL;DR: Vesting under the 2023 LTIP and tax-withholding are standard; disclosures appear complete and compliant.

The Form 4 identifies awards granted under the 2023 Long-Term Incentive Plan with vesting schedules and confirms shares were withheld to meet tax obligations. The signature is by an attorney-in-fact, and the explanatory footnotes clarify the nature of RSUs and vesting timing. From a governance perspective, the filing provides the necessary detail about award origin and withholding, consistent with Section 16 reporting expectations.

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)
08/15/2025

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	08/15/2025		M		1,437	A	$0	22,656	D
Common Stock	08/15/2025		F		730(1)	D	$10.82	21,926	D
Common Stock	08/15/2025		M		898	A	$0	22,824	D
Common Stock	08/15/2025		F		457(1)	D	$10.82	22,367	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(2)	(3)	08/15/2025		M			1,437	(4)	(4)	Common Stock	1,437	$0	4,311	D
Restricted Stock Unit(5)	(3)	08/15/2025		M			898	(6)	(6)	Common Stock	898	$0	6,281	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. 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).

3. 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.

4. 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.

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

6. RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2025, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.

Remarks:

	/s/ Rachel Malina, Attorney-in-Fact for Rick A. Carpenter	08/19/2025
	** 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 transactions did TNDM CTO Rick Carpenter report on Form 4?

He reported RSU vesting and related withholding on 08/15/2025: 1,437 and 898 RSU shares vested (issued at $0) and 730 and 457 shares were withheld to satisfy tax withholding.

Were any shares sold by Rick Carpenter in these transactions?

No. The filing states the withheld shares were used to satisfy tax withholding and explicitly notes that no shares were sold.

Under what plan were the RSUs awarded?

The awards were made under the Tandem Diabetes Care, Inc. 2023 Long-Term Incentive Plan as described in the form's explanatory notes.

What vesting schedule applies to these RSUs?

RSUs vest 33% on 5/15 of the initial year (2024 or 2025 depending on award) with the remainder vesting in eight equal quarterly installments, per the filing explanations.

How did these transactions affect Carpenter's beneficial ownership?

The filing lists resulting common stock beneficial ownership balances between 21,926 and 22,824 shares and derivative (RSU) balances at 4,311 and 6,281 shares following the reported entries.