Tandem (TNDM) CFO Leigh Vosseller reports both purchase and sale of shares

Rhea-AI Filing Summary

Insider Form 4 for Tandem Diabetes Care (TNDM)

Leigh Vosseller, EVP & Chief Financial Officer, reported a purchase of 13,720 shares of Tandem common stock on 08/08/2025 at a weighted average price of $10.8895. The filing states the trades were executed in multiple trades at prices ranging from $10.86 to $10.90. The report also shows a reported disposition of 33,798 shares (table entry lists the amount as a disposition without a transaction date or price). The filing notes that certain securities are held by the Leigh A. Vosseller Trust dated January 17, 2010, for which Ms. Vosseller is trustee, and lists 25,580 shares as beneficially owned following the reported transaction(s).

Insights

Financial Analyst

TL;DR: CFO reported a small open-market purchase of 13,720 shares but the filing also shows a significant 33,798-share disposition.

The purchase at a weighted average of $10.8895 executed in multiple trades indicates an affirmative acquisition on 08/08/2025, which investors often view as a positive signal when held by a senior officer. However, the separate table entry showing a 33,798-share disposition is material in size and lacks date/price detail in the table, complicating interpretation of net insider intent. Holdings are also partially held through a family trust, which affects direct/indirect ownership reporting.

Corporate Governance Expert

TL;DR: Disclosure is compliant but mixed activity and missing disposition details reduce clarity for stakeholders.

The Form 4 discloses both acquisition and disposition activity by the reporting person and includes the required explanation of purchase pricing ranges. The filing properly identifies indirect holdings via the Leigh A. Vosseller Trust. The lack of explicit date and price for the 33,798-share disposition line in the table reduces transparency and may prompt requests for further detail from regulators or investors seeking to reconcile net changes in beneficial ownership.

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

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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^*

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)
08/08/2025

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	08/08/2025		P		13,720	A	$10.8895(1)	25,580	I	Leigh A. Vosseller Trust(2)
Common Stock								33,798	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

Explanation of Responses:

1. This transaction was executed in multiple trades at prices ranging from $10.86 to $10.90 per share. The reported price reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.

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

Remarks:

	/s/ Rachel Malina, Attorney-in-Fact for Leigh A. Vosseller	08/11/2025
	** 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.
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