STOCK TITAN

Tandem Diabetes (TNDM) CFO exercises RSUs and ESPP, increases share holdings

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Tandem Diabetes Care EVP & Chief Financial Officer Leigh Vosseller reported several equity compensation transactions in company stock. On May 15, 2026, she exercised restricted stock units converting a total of 13,495 shares of common stock, and 4,843 shares were withheld by the company to cover tax obligations, with no shares sold. She also acquired 1,336 shares through the company’s Employee Stock Purchase Plan at $10.90 per share. Following these transactions, she directly holds 40,374 shares of common stock and an additional 25,580 shares are held indirectly through the Leigh A. Vosseller Trust.

Positive

  • None.

Negative

  • None.
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 Restricted Stock Unit 10,496 $0.00 --
Exercise Common Stock 1,503 $0.00 --
Tax Withholding Common Stock 540 $12.82 $7K
Exercise Common Stock 1,496 $0.00 --
Tax Withholding Common Stock 537 $12.82 $7K
Exercise Common Stock 10,496 $0.00 --
Tax Withholding Common Stock 3,766 $12.82 $48K
Grant/Award Common Stock 1,336 $10.90 $15K
holding Common Stock -- -- --
Holdings After Transaction: Restricted Stock Unit — 0 shares (Direct, null); Common Stock — 40,914 shares (Direct, null); 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 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 November 18, 2025, through May 15, 2026. This transaction is also exempt under Rule 16b-3(c). 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. Awarded on May 30, 2025 pursuant to the 2023 Plan. RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2026, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.
RSU-derived shares 13,495 shares Common stock from RSU exercises and conversions on May 15, 2026
Tax withholding shares 4,843 shares Shares withheld by Tandem Diabetes Care to satisfy tax obligations
ESPP purchase 1,336 shares at $10.90 Acquired through Amended and Restated 2013 Employee Stock Purchase Plan
Direct holdings after transactions 40,374 shares Common stock directly owned by Leigh Vosseller following transactions
Trust holdings 25,580 shares Common stock held by the Leigh A. Vosseller Trust
RSU exercise batches 10,496; 1,496; 1,503 shares Three RSU exercises (M-coded) into common stock on May 15, 2026
Tax-withheld batches 3,766; 537; 540 shares Three F-coded tax withholding dispositions at $12.82 per share
Restricted Stock Unit financial
"security_title: "Restricted Stock Unit" with derivative exercises into common stock"
A restricted stock unit is a promise from a company to give an employee shares of stock after certain conditions are met, like staying with the company for a set amount of time. It’s like earning a bonus that turns into company stock once you’ve proven your commitment, making it a way to motivate and reward employees.
Employee Stock Purchase Plan financial
"acquisition of shares pursuant to the Tandem Diabetes Care, Inc. Amended and Restated 2013 Employee Stock Purchase Plan (ESPP)"
An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.
tax withholding requirements financial
"Shares withheld by Tandem Diabetes Care Inc. to satisfy tax withholding requirements on vesting of RSU"
Rule 16b-3(c) regulatory
"ESPP acquisition is described as exempt under Rule 16b-3(c)"
An SEC rule that lets corporate insiders avoid automatic "short‑swing" profit recovery when they buy or sell their company’s stock under a pre‑approved, written plan that meets specific conditions. For investors, it matters because it clarifies when insider trades are treated as routine, reducing legal uncertainty and helping distinguish trades made for ordinary compensation or pre‑planned reasons from those that might signal opportunistic or timely insider advantage.
Long-Term Incentive Plan financial
"RSU awards granted pursuant to the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan"
A long-term incentive plan is a company program that pays executives or employees with stock, options, or cash tied to multi-year performance goals, where the rewards become theirs only after meeting conditions over time. Think of it as a delayed bonus or retirement-style reward that aligns employees’ interests with shareholders by encouraging them to boost long-term value; investors watch these plans because they affect pay costs, share dilution and management incentives.
SEC Form 4
FORM 4UNITED 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 CALIFORNIA 92130

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
TANDEM DIABETES CARE INC [ TNDM ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
Director10% Owner
XOfficer (give title below)Other (specify below)
EVP & CHIEF FINANCIAL OFFICER
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
05/15/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
CodeVAmount(A) or (D)Price
Common Stock05/15/2026M1,503A$040,914D
Common Stock05/15/2026F(1)540D$12.8240,374D
Common Stock05/15/2026M1,496A$041,870D
Common Stock05/15/2026F(1)537D$12.8241,333D
Common Stock05/15/2026M10,496A$051,829D
Common Stock05/15/2026F(1)3,766D$12.8248,063D
Common Stock05/15/2026A(2)1,336A$10.949,399D
Common Stock25,580ILeigh A. Vosseller Trust(3)
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Restricted Stock Unit(4)(5)05/15/2026M1,503 (6) (6)Common Stock1,503$00D
Restricted Stock Unit(7)(5)05/15/2026M1,496 (8) (8)Common Stock1,496$05,982D
Restricted Stock Unit(9)(5)05/15/2026M10,496 (10) (10)Common Stock10,496$020,992D
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 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 November 18, 2025, through May 15, 2026. This transaction is also exempt under Rule 16b-3(c).
3. The securities are held by the Leigh A. Vosseller Trust dated January 17, 2010, of which Leigh Vosseller is the Trustee.
4. 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).
5. 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.
6. 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.
7. Awarded on May 23, 2024 pursuant to the 2023 Plan.
8. 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.
9. Awarded on May 30, 2025 pursuant to the 2023 Plan.
10. RSU vest as to thirty-three percent (33%) of the total number of shares subject to the RSU on 5/15/2026, and the remaining shares shall vest in eight (8) equal quarterly installments thereafter.
Remarks:
/s/ Shannon M. Hansen, Attorney-in-Fact for Leigh A. Vosseller05/19/2026
** Signature of Reporting PersonDate
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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transactions did TNDM CFO Leigh Vosseller report?

Leigh Vosseller reported equity compensation activity including RSU vesting, tax withholding, and an ESPP purchase. She exercised restricted stock units into 13,495 common shares, with 4,843 shares withheld for taxes, and bought 1,336 shares through the employee stock purchase plan.

Did the TNDM CFO sell any Tandem Diabetes Care shares in this Form 4?

No, the filing states that no shares were sold. Shares labeled with transaction code F were withheld by Tandem Diabetes Care to satisfy tax obligations on RSU vesting, meaning they covered taxes rather than representing open-market sales.

How many Tandem Diabetes Care shares does the TNDM CFO hold after these transactions?

After the reported transactions, Leigh Vosseller directly holds 40,374 shares of Tandem Diabetes Care common stock. An additional 25,580 shares are held indirectly through the Leigh A. Vosseller Trust, where she serves as trustee, according to the filing footnotes.

What was the size and price of the ESPP purchase reported by TNDM’s CFO?

The Form 4 reports an acquisition of 1,336 shares of Tandem Diabetes Care common stock through the company’s employee stock purchase plan. These ESPP shares were acquired at a purchase price of $10.90 per share for the period ending May 15, 2026.

How many shares were exercised and withheld for taxes in the TNDM Form 4?

The filing shows 13,495 shares acquired through RSU exercises and related derivative conversions. Of these, 4,843 shares were withheld by Tandem Diabetes Care to satisfy tax withholding requirements on vesting, as specifically described in a footnote to the Form 4.

How are shares attributed to the Leigh A. Vosseller Trust in the TNDM filing?

The Form 4 notes 25,580 Tandem Diabetes Care shares held by the Leigh A. Vosseller Trust dated January 17, 2010. A footnote explains that Leigh Vosseller is the trustee, so these shares are reported as indirect beneficial ownership associated with her.