9. Convertible Notes

For the six months ended June 30, 2026, convertible notes with a face value of $0.1 million were converted, at the option of the holder, into approximately 0.8 million shares of our common stock and convertible notes with a face value of $0.05 million were repaid upon maturity.  For the six months ended June 30, 2025, convertible notes with a face value of $0.4 million were converted, at the option of the holder, into approximately 2.8 million shares of our common stock, including $0.2 million of convertible notes held by related parties. 

Additionally, during the six months ended June 30, 2026, we entered into exchange agreements to exchange outstanding principal and accrued interest of approximately $0.7 million of convertible notes for unregistered shares of our common stock (see Note 13).

We recognized interest expense on our convertible debt of approximately $0.1 million for each of the six months ended June 30, 2026 and 2025, respectively.  During each of the six months ended June 30, 2026 and 2025, we elected to pay approximately $0.1 million of interest in shares of our common stock and issued approximately 0.4 million shares of our common stock as interest-in-kind payments in each period.

Convertible notes payable at  June 30, 2026 and  December 31, 2025 consist of the following (in thousands):

¹  Unless otherwise revoked by the holder within ten days of the then-stated maturity date, the maturity date of the note will automatically extend by one year, for a maximum of ten years.