[Form 4] TANDEM DIABETES CARE INC Insider Trading Activity

Rhea-AI Filing Summary

Rick A. Carpenter, Chief Technology Officer of Tandem Diabetes Care, reported transactions on 09/15/2025 affecting his holdings of TNDM common stock. 406 restricted stock units (RSUs) vested and were recorded as acquired under code M with a $0 price, leaving 22,773 shares beneficially owned after the transaction. Separately, 207 shares were disposed of under code F(1) at $12.09 per share, leaving 22,566 shares reported as beneficially owned following that disposition. The filing states that the Company withheld shares to satisfy tax withholding on RSU vesting and that no shares were sold to cover taxes. The RSUs were originally awarded on 12/15/2021 under the 2013 Stock Incentive Plan and vest 25% on 12/15/2022 with the remainder vesting in twelve equal quarterly installments.

Positive

• RSU vesting recorded (406 RSUs) indicating routine compensation rather than opportunistic selling
• Tax withholding via share retention rather than open-market sales, as disclosed in the filing

Negative

• Disposition of 207 shares at $12.09 reduced reported beneficial ownership modestly

Insights

Financial Analyst

TL;DR: Insider received RSU vesting and a small disposition; overall ownership change is immaterial to company valuation.

The report documents routine compensation-related activity: vesting of 406 RSUs and a related disposition of 207 shares at $12.09 per share, with share withholding used to satisfy taxes rather than a cash sale. The net change in reported beneficial ownership is modest (from documented figures), and there is no indication of large-scale selling pressure or material dilution beyond standard employee compensation mechanics. For investors, this is a standard insider compensation event rather than a signal of operational or financial change.

Corporate Governance Expert

TL;DR: Disclosure aligns with Section 16 reporting rules and internal compensation plans; documentation is complete.

The Form 4 clearly identifies the reporting person, relationship (Chief Technology Officer), transaction dates, codes (M for RSU vesting and F(1) for disposition), and explains tax-withholding treatment. The filing references the 2013 Stock Incentive Plan and the original award date (12/15/2021), and includes vesting schedule language. The signature is provided by an attorney-in-fact, meeting procedural requirements. There are no governance red flags or missing required disclosures in the provided content.

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
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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).

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)
09/15/2025

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	09/15/2025		M		406	A	$0	22,773	D
Common Stock	09/15/2025		F(1)		207	D	$12.09	22,566	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)	09/15/2025		M			406	(4)	(4)	Common Stock	406	$0	406	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 December 15, 2021 pursuant to the Tandem Diabetes Care, Inc. 2013 Stock Incentive Plan, as amended, and the agreements related thereto (the 2013 Plan).

3. 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 2013 Plan.

4. RSU vest as to twenty-five percent (25%) of the total number of shares subject to the RSU on 12/15/2022, and the remaining shares shall vest in twelve (12) equal quarterly installments thereafter.

Remarks:

	/s/ Rachel Malina, Attorney-in-Fact for Rick A. Carpenter	09/16/2025
	** 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 Rick A. Carpenter report for TNDM on 09/15/2025?

He reported vesting of 406 RSUs (code M) and a disposition of 207 shares (code F(1)) at $12.09 per share.

How many TNDM shares does Rick Carpenter beneficially own after these transactions?

The filing reports 22,773 shares after the RSU vesting transaction and 22,566 shares after the disposition.

Were any shares sold on the open market to cover taxes for the vested RSUs?

No; the filing states shares were withheld by Tandem Diabetes Care to satisfy tax withholding and no shares were sold.

What is the origin and vesting schedule of the RSUs reported?

The RSUs were awarded on 12/15/2021 under the Tandem Diabetes Care, Inc. 2013 Stock Incentive Plan; 25% vested on 12/15/2022 with the remainder vesting in twelve equal quarterly installments.

Who signed the Form 4 filing for Rick Carpenter?

The form is signed by Rachel Malina, Attorney-in-Fact, for Rick A. Carpenter on 09/16/2025.