TECX · Tectonic Therapeutic, Inc. · Insider Trading

This sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $22.61 to $23.32, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

This transaction reported represents the withholding of shares by the Issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of the restricted stock units granted on September 25, 2025.

This transaction reported represents the withholding of shares by the Issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of the restricted stock units granted on September 25, 2025.

This transaction reported represents the withholding of shares by the Issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of the restricted stock units granted on September 25, 2025.

This transaction reported represents the withholding of shares by the Issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of the restricted stock units granted on September 25, 2025.

This transaction reported represents the withholding of shares by the Issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of the restricted stock units granted on September 25, 2025.

1/8th of the shares subject to the option vest on September 3, 2026 with the remaining shares subject to the option vesting in the following 42 equal monthly installments beginning on October 3, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

1/8th of the shares subject to the option vest on September 3, 2026 with the remaining shares subject to the option vesting in the following 42 equal monthly installments beginning on October 3, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

1/8th of the shares subject to the option vest on September 3, 2026 with the remaining shares subject to the option vesting in the following 42 equal monthly installments beginning on October 3, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

1/8th of the shares subject to the option vest on September 3, 2026 with the remaining shares subject to the option vesting in the following 42 equal monthly installments beginning on October 3, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

1/8th of the shares subject to the option vest on September 3, 2026 with the remaining shares subject to the option vesting in the following 42 equal monthly installments beginning on October 3, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

The shares subject to the option vest in 48 equal monthly installments beginning on October 25, 2025, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

The shares subject to the option vest in 48 equal monthly installments beginning on October 25, 2025, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

The shares subject to the option vest in 48 equal monthly installments beginning on October 25, 2025, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

This exercise and subsequent sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

This transaction reported represents the withholding of shares by the Issuer to satisfy the Reporting Person's tax withholding obligations in connection with the vesting and settlement of the restricted stock units granted on December 4, 2024.

Represents the number of shares earned under a performance-based stock option award based on the Issuer's satisfaction of certain performance criteria. In light of the performance-based conditions of the option award, the option was not reportable under Section 16 until the performance conditions were certified by the Issuer's Board of Directors, which occurred on June 11, 2026. The option reported on this form represents 50% of the total number of shares underlying the performance option subject to the option award. The remaining 50% of the shares will be earned upon the satisfaction of additional performance criteria.

The shares underlying the option are fully vested and immediately exercisable as of June 1, 2026.

The option shall vest in full on the earliest of (i) June 9, 2027, (ii) the date of the Issuer's 2027 Annual Meeting of Stockholders, or (iii) a "Change in Control" (as defined in the Issuer's 2024 Equity Incentive Plan) of the Issuer, subject in each case, to the Reporting Person providing continuous service to the Issuer on each such date.

The option shall vest in full on the earliest of (i) June 9, 2027, (ii) the date of the Issuer's 2027 Annual Meeting of Stockholders, or (iii) a "Change in Control" (as defined in the Issuer's 2024 Equity Incentive Plan) of the Issuer, subject in each case, to the Reporting Person providing continuous service to the Issuer on each such date.

The option shall vest in full on the earliest of (i) June 9, 2027, (ii) the date of the Issuer's 2027 Annual Meeting of Stockholders, or (iii) a "Change in Control" (as defined in the Issuer's 2024 Equity Incentive Plan) of the Issuer, subject in each case, to the Reporting Person providing continuous service to the Issuer on each such date.

The option shall vest in full on the earliest of (i) June 9, 2027, (ii) the date of the Issuer's 2027 Annual Meeting of Stockholders, or (iii) a "Change in Control" (as defined in the Issuer's 2024 Equity Incentive Plan) of the Issuer, subject in each case, to the Reporting Person providing continuous service to the Issuer on each such date.

One-third (1/3) of the shares subject to the option shall vest on June 8, 2027, and the balance shall vest in 24 equal monthly installments thereafter, subject in each case to the Reporting Person providing continuous service to the Issuer on each such date.

This sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on April 8, 2025.

One Third (1/3) of the shares subject to the option shall vest on April 1, 2027, and the balance shall vest in 24 equal monthly installments thereafter, subject in each case, to the Reporting Person providing continuous service to the Issuer through each applicable vesting date.

This sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on April 8, 2025.

This sale was made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on April 8, 2025.

These exercises and sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

Received in exchange for a stock option to acquire 71,029 shares of common stock pursuant to that certain merger, as more fully described on the Reporting Person's Form 4 filed with the Securities and Exchange Commission on June 24, 2024. https://www.sec.gov/Archives/edgar/data/1681087/000141588924017962/xslF345X05/form4-06242024_080611.xml

25% of the shares subject to the option vested on June 1, 2022; and the remainder of the shares subject to the option vest in 36 equal monthly installments with the final amount vesting on June 1, 2025, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

These exercises and sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

These exercises and sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

These exercises and sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

The shares subject to the option vest in 48 equal monthly installments beginning on October 25, 2025, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

These exercises and sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

These exercises and sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

These shares are represented by restricted stock units. Each restricted stock unit represents a contingent right to receive one share of common stock of the Issuer. The shares shall vest in 3 equal annual installments on each of March 4, 2027, March 4, 2028 and March 4, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

The shares subject to the option vest in 48 equal monthly installments beginning on April 4, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

These sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

These shares are represented by restricted stock units. Each restricted stock unit represents a contingent right to receive one share of common stock of the Issuer. The shares shall vest in 3 equal annual installments on each of March 4, 2027, March 4, 2028 and March 4, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

These shares are represented by restricted stock units. Each restricted stock unit represents a contingent right to receive one share of common stock of the Issuer. The shares shall vest in 3 equal annual installments on each of March 4, 2027, March 4, 2028 and March 4, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

These shares are represented by restricted stock units. Each restricted stock unit represents a contingent right to receive one share of common stock of the Issuer. The shares shall vest in 3 equal annual installments on each of March 4, 2027, March 4, 2028 and March 4, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

These shares are represented by restricted stock units. Each restricted stock unit represents a contingent right to receive one share of common stock of the Issuer. The shares shall vest in 3 equal annual installments on each of March 4, 2027, March 4, 2028 and March 4, 2029, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

The shares subject to the option vest in 48 equal monthly installments beginning on April 4, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

The shares subject to the option vest in 48 equal monthly installments beginning on April 4, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

The shares subject to the option vest in 48 equal monthly installments beginning on April 4, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

The shares subject to the option vest in 48 equal monthly installments beginning on April 4, 2026, subject to the Reporting Person's continued service to the Issuer on each such vesting date.

These sales were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 14, 2025.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $21.02 to $21.15, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

These shares are held by the Reicin-Boiarsky Family Trust (the "Trust"). The Reporting Person's spouse is a co-trustee of the Trust. Accordingly, the Reporting Person may be deemed to have shared voting and dispositive power over the securities held by the Trust. The Reporting Person disclaims beneficial ownership of the shares held by the Trust except to the extent of her pecuniary interest therein, and this report shall not be deemed an admission that the Reporting Person is the beneficial owner of these securities for purposes of Section 16 or for any other purpose.