Company: QTIWW
Filing Date: 2025-12-31
Form Type: 424B3
Source: 0001628280-25-059235
Chunk: 440

Company: QT IMAGING HOLDINGS, INC.
Filing Date: 2025-12-31
Form: 424B3
Chunk 440
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              2.41 |     |     | $    | 2.22 |     |
| Expected option term (years)   |     |      |                    | 5.9 |     |      |      | 5.7 |     |      |                   | 5.5 |     |      |      | 5.7 |
| Expected volatility            |     |      |               71.4 |   % |     |      | 67.9 |   % |     |      |              71.3 |   % |     |      | 67.9 |   % |
| Risk-free rate of return       |     |      |                3.9 |   % |     |      |  4.3 |   % |     |      |               4.0 |   % |     |      |  4.3 |   % |
| Expected annual dividend yield |     |      |                  — |   % |     |      |    — |   % |     |      |                 — |   % |     |      |    — |   % |

Option pricing models require the input of various subjective assumptions, including the option’s expected life and the price volatility of the underlying stock. The expected stock price volatility is based on the analysis of volatilities of the Company’s selected public peer group over a period commensurate with the expected term of the options. The expected term of employee options represents the weighted-average period the options are expected to remain outstanding and was derived using the simplified method for awards that qualify for its “plain-vanilla” options. All awards that are outstanding are qualified for “plain-vanilla” options. The risk-free interest rate is based on the U.S. Treasury interest rates whose term in consistent with the expected life of the stock options. No dividend

<div align='center'>F-78</div>

#### QT IMAGING HOLDINGS, INC.

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

yield is included as the Company has not issued any dividends and do not anticipate issuing any dividends in the future.

The following table shows stock-based compensation expense by functional area in the condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2025 and 2024:

|                                     |     | 2025 | Three Months Ended 
      September 30, |     | 2024 |