Company: QTIWW
Filing Date: 2025-12-31
Form Type: 424B3
Source: 0001628280-25-059235
Chunk: 414

Company: QT IMAGING HOLDINGS, INC.
Filing Date: 2025-12-31
Form: 424B3
Chunk 414
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 and corporate event features were deemed to be de minimis.

The Company and Yorkville entered into that certain Termination Agreement, dated February 26, 2025 (the “Termination Agreement”), pursuant to which the parties acknowledged the termination of the SEPA and the Yorkville Note, effective as of February 26, 2025. As such, on the effective date of the Termination Agreement, the derivative liability was deemed to be extinguished. The Company recorded the change in fair value of the derivative liability within the condensed consolidated statements of operations and comprehensive loss as of the date immediately prior to the effective date of the Termination Agreement.

Significant assumptions used in the valuation of the fair value of the derivative liability as of December 31, 2024 and February 26, 2025 were as follows:

|                            |     |   | February 26, 2025 |      |     |   | December 31, 2024 |      |
|:---------------------------|:----|:--|------------------:|-----:|:----|:--|------------------:|-----:|
| Fair value of common stock |     | $ |              1.23 |      |     | $ |              1.47 |      |
| Term in years              |     |   |                   | 1.11 |     |   |                   | 1.26 |
| Volatility                 |     |   |             125.0 |    % |     |   |             120.0 |    % |
| Risk-free rate             |     |   |               4.1 |    % |     |   |               4.2 |    % |
| Debt discount              |     |   |              30.0 |    % |     |   |              30.0 |    % |

The activity for the fair value of the derivative liability during the nine months ended September 30, 2025 was as follows:

<div align='center'>F-66</div>

#### QT IMAGING HOLDINGS, INC.

### Notes to Condensed Consolidated Financial Statements
<div align='center'>(Unaudited)</div>

|                                                                  |     | Derivative Liability |         |          |
|:-----------------------------------------------------------------|:----|:---------------------|--------:|---------:|
| Beginning balance, January 1, 2025                               |     | $                    | 303,300 |          |
| Extinguishment upon Ter