Leigh Vosseller, Executive Vice President and Chief Financial Officer of Tandem Diabetes Care Inc. (NASDAQ:TNDM), filed a Form 4 on August 18, 2026, disclosing restricted stock unit vesting transactions dated August 15, 2026.

Key Highlights

  • RSU vesting (May 2024 grant): 1,496 shares acquired via RSU vesting at $0 cost on August 15, 2026, with 537 shares withheld for tax purposes at $22.72 per share.
  • RSU vesting (May 2025 grant): 2,624 shares acquired via RSU vesting at $0 cost on August 15, 2026, with 942 shares withheld for tax purposes at $22.72 per share.
  • No open-market sales: According to the filing, shares were withheld by the issuer to satisfy tax withholding requirements upon RSU vesting and no shares were sold.
  • Direct beneficial ownership: Following the transactions, Vosseller directly holds 52,040 shares of common stock.
  • Indirect beneficial ownership: An additional 25,580 shares are held indirectly through the Leigh A. Vosseller Trust dated January 17, 2010, of which Leigh Vosseller is the Trustee.
  • Remaining RSUs: 4,486 RSUs from the May 23, 2024 grant and 18,368 RSUs from the May 30, 2025 grant remain outstanding following the reported transactions.

RSU Vesting Details for Tandem Diabetes Care CFO Leigh Vosseller

According to the Form 4 filing, Leigh Vosseller, EVP and Chief Financial Officer of Tandem Diabetes Care Inc. (NASDAQ:TNDM), reported two separate RSU vesting events on August 15, 2026. The first involved 1,496 RSUs originally awarded on May 23, 2024, under the Tandem Diabetes Care Inc. 2023 Long-Term Incentive Plan, as amended. The second involved 2,624 RSUs awarded on May 30, 2025, also under the 2023 Plan. Both sets of RSUs were acquired at $0 conversion price.

The filing discloses that 537 shares and 942 shares, respectively, were withheld by the issuer to satisfy tax withholding requirements upon vesting, at a price of $22.72 per share. The filing states explicitly that no shares were sold. Per the vesting schedules described in the filing, one-third of the May 2024 RSUs vested on May 15, 2025, with remaining RSUs vesting in eight equal quarterly installments thereafter. Similarly, one-third of the May 2025 RSUs vested on May 15, 2026, with remaining RSUs vesting in eight equal quarterly installments thereafter, subject to the terms of the 2023 Plan.

Following all reported transactions, the filing shows Vosseller directly owns 52,040 shares and indirectly holds 25,580 shares through the Leigh A. Vosseller Trust. Each RSU, as described in the filing, "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." The Form 4 was signed by Jerilyn Laskie as Attorney-in-Fact for Leigh A. Vosseller on August 18, 2026.

What Was Disclosed

The filing reports RSU vesting transactions for Tandem Diabetes Care's CFO on August 15, 2026, covering two separate grants. Shares were withheld for taxes at $22.72 per share, with no open-market sales occurring. Direct ownership following the transactions stands at 52,040 shares.