Leigh A. Vosseller - 15 Aug 2026 Form 4 Insider Report for TANDEM DIABETES CARE INC (TNDM)

Reporting relationship: EVP & CHIEF FINANCIAL OFFICER
Issuer ticker: TNDM
Reported as of: 15 Aug 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 18 Aug 2026, 16:28:49 UTC
Prior SEC filing: 02 Jun 2026
Source filing: View source filing
Reporting owner signature: /s/ Jerilyn Laskie, Attorney-in-Fact for Leigh A. Vosseller

Key filing fact

Leigh A. Vosseller filed Form 4 for TANDEM DIABETES CARE INC (TNDM) on 18 Aug 2026.

Key facts

This page summarizes Leigh A. Vosseller's Form 4 filing for TANDEM DIABETES CARE INC (TNDM).
6 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 18 Aug 2026, 16:28.

Change

Previous filing in this sequence was filed on 02 Jun 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001726322 Primary reporting owner

Vosseller Leigh

Relationship: EVP & CHIEF FINANCIAL OFFICER
Address: 12400 HIGH BLUFF DRIVE, SAN DIEGO
Signature: /s/ Jerilyn Laskie, Attorney-in-Fact for Leigh A. Vosseller
Signature date: 18 Aug 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

TNDM transaction

Common Stock

Options Exercise

Transaction value
Shares: +1,496
Change %: +3%
Price: $0.000000^*
Shares after: 50,895
Date: 15 Aug 2026
Ownership: Direct

TNDM transaction

Common Stock

Tax liability

Transaction value
Shares: -537
Change %: -1.1%
Price: $22.72^*
Shares after: 50,358
Date: 15 Aug 2026
Ownership: Direct
Footnotes: F1

TNDM transaction

Common Stock

Options Exercise

Transaction value
Shares: +2,624
Change %: +5.2%
Price: $0.000000^*
Shares after: 52,982
Date: 15 Aug 2026
Ownership: Direct

TNDM transaction

Common Stock

Tax liability

Transaction value
Shares: -942
Change %: -1.8%
Price: $22.72^*
Shares after: 52,040
Date: 15 Aug 2026
Ownership: Direct
Footnotes: F1

TNDM holding

Common Stock

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after: 25,580
Date: 15 Aug 2026
Ownership: Leigh A. Vosseller Trust
Footnotes: F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

TNDM transaction Derivative

Restricted Stock Unit

Options Exercise

Transaction value
Shares: -1,496
Change %: -25%
Price: $0.000000^*
Shares after: 4,486
Date: 15 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 1,496
Exercise price
Footnotes: F3, F4, F5

TNDM transaction Derivative

Restricted Stock Unit

Options Exercise

Transaction value
Shares: -2,624
Change %: -12%
Price: $0.000000^*
Shares after: 18,368
Date: 15 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 2,624
Exercise price
Footnotes: F4, F6, F7

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 7 footnotes

Footnote F1

Shares withheld by the Issuer to satisfy tax withholding requirements upon the vesting of restricted stock units (RSUs). No shares were sold.

Footnote F2

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

Footnote F3

Awarded on May 23, 2024 pursuant to the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, as amended, and agreements related thereto (the 2023 Plan).

Footnote F4

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.

Footnote F5

One-third of the RSUs granted on May 23, 2024 vested on May 15, 2025, with the remaining RSUs vesting in eight (8) equal quarterly installments thereafter, subject to the terms of the 2023 Plan.

Footnote F6

Awarded on May 30, 2025 pursuant to the 2023 Plan.

Footnote F7

One-third of the RSUs granted on May 30, 2025 vested on May 15, 2026, with the remaining RSUs vesting in eight (8) equal quarterly installments thereafter, subject to the terms of the 2023 Plan.