FULC · Fulcrum Therapeutics, Inc.

These shares were purchased in multiple transactions at prices ranging from $3.46 to $3.55.

Tang Capital Partners, LP ("TCP") beneficially owns 1,668,554 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 2,212,803 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 1,668,539 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 1,531,049 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

The prices reported are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $3.50 to $3.60. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the SEC staff, upon request, all information regarding the number of shares purchased at each price within the ranges set forth in Footnotes 1 and 3.

Tang Capital Partners, LP ("TCP") beneficially owns 1,668,554 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 2,212,803 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 1,668,539 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 1,531,049 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

These shares were purchased in multiple transactions at prices ranging from $3.50 to $3.60.

Tang Capital Partners, LP ("TCP") beneficially owns 1,630,142 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 2,160,423 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 1,630,127 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 1,492,637 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

These shares were purchased in multiple transactions at prices ranging from $3.54 to $3.60.

Tang Capital Partners, LP ("TCP") beneficially owns 1,630,142 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 2,160,423 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 1,630,127 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 1,492,637 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

These shares were purchased in multiple transactions at prices ranging from $3.53 to $3.60.

Tang Capital Partners, LP ("TCP") beneficially owns 1,630,142 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 2,160,423 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 1,630,127 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 1,492,637 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

The prices reported are weighted-average prices. These shares were purchased in multiple transactions at prices ranging from $3.54 to $3.55. The Reporting Persons undertake to provide the Issuer, any security holder of the Issuer or the SEC staff, upon request, all information regarding the number of shares purchased at each price within the ranges set forth in Footnotes 1 and 3 through 5.

Tang Capital Partners, LP ("TCP") beneficially owns 1,630,142 shares, Tang Capital Partners International, LP ("TCPI") beneficially owns 2,160,423 shares, Tang Capital Partners III, Inc. ("TCP III") beneficially owns 1,630,127 shares, and Tang Capital Partners IV, Inc. ("TCP IV") beneficially owns 1,492,637 shares. Kevin Tang is the sole manager of Tang Capital Management, LLC, which is the general partner of TCP and TCPI. Kevin Tang is the sole director and Chief Executive Officer of TCP III and TCP IV, which are indirectly wholly owned by TCP. Mr. Tang has a pecuniary interest in the shares beneficially held by TCP, TCPI, TCP III and TCP IV.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 30, 2026 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 27, 2026.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.555 to $3.82, inclusive. The reporting person undertakes to provide to Fulcrum Therapeutics, Inc., any security holder of Fulcrum Therapeutics, Inc. 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 (2) to this Form 4.

This option was granted on April 23, 2026 and is scheduled to vest in equal monthly installments until April 23, 2029, subject to continued service.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 1, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.48 to $11.10, inclusive. The reporting person undertakes to provide to Fulcrum Therapeutics, Inc., any security holder of Fulcrum Therapeutics, Inc. 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 (2) to this Form 4.

This option was granted on February 2, 2026 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2026, subject to the reporting person's continued service on each such vesting date.

This option was granted on February 2, 2026 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2026, subject to the reporting person's continued service on each such vesting date.

This option was granted on February 2, 2026 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2026, subject to the reporting person's continued service on each such vesting date.

This option was granted on February 2, 2026 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2026, subject to the reporting person's continued service on each such vesting date.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 1, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.60 to $11.33, inclusive. The reporting person undertakes to provide to Fulcrum Therapeutics, Inc., any security holder of Fulcrum Therapeutics, Inc. 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 (2) to this Form 4. This Form 4/A corrects the weighted average price indicated in the Form 4 submitted on January 6, 2026 from $11.8726 to $10.8726.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 8, 2025.

Includes 10,252 shares that were previously acquired under the Issuer's employee stock purchase plan.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $12.81 to $13.8099 inclusive. The Reporting Persons undertake 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.

RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund. The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

Held directly by the Fund.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $14.81 to $15.39 inclusive. The Reporting Persons undertake 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.

RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund. The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

Held directly by the Fund.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.81 to $14.805 inclusive. The Reporting Persons undertake 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.

RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund. The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

Held directly by the Fund.

The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on August 1, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $10.50 to $11.18, inclusive. The reporting person undertakes to provide to Fulcrum Therapeutics, Inc., any security holder of Fulcrum Therapeutics, Inc. 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 (2) to this Form 4.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 26, 2025 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

The sale reported on this Form 4 represents shares required to be sold by the Reporting Person to cover tax withholding obligations in connection with the vesting of restricted stock units. The sale occurred automatically to satisfy the tax withholding obligations to be funded by a "sell to cover" transaction and does not represent a discretionary trade by the Reporting Person.

Includes 2,989 shares acquired under the Issuer's employee stock purchase plan on May 14, 2024.

This option was granted on January 24, 2025 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2025, subject to the reporting person's continued service on each such vesting date.

This option was granted on January 24, 2025 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2025, subject to the reporting person's continued service on each such vesting date.

This option was granted on January 24, 2025 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2025, subject to the reporting person's continued service on each such vesting date.

This option was granted on January 24, 2025 and is scheduled to vest in equal quarterly installments over four years beginning on the vesting commencement date of January 1, 2025, subject to the reporting person's continued service on each such vesting date.

This option was granted on November 12, 2024 and is scheduled to vest in equal monthly installments until November 12, 2027, subject to continued service.

RA Capital Healthcare Fund, L.P. (the "Fund") entered into an Exchange Agreement with the Issuer pursuant to which the Fund exchanged, on a 1:1 basis, 8,500,000 shares of the Issuer's Common Stock for an equal number of prefunded warrants, each to purchase one share of the Issuer's Common Stock at an exercise price of $0.001 per share (each a "Pre-Funded Warrant").

The Pre-Funded Warrants have no expiration date and are exercisable immediately. Notwithstanding the foregoing, the Reporting Persons shall not be entitled to exercise the Pre-Funded Warrant if it would cause the aggregate number of shares of Common Stock beneficially owned by the Reporting Persons, their affiliates and any persons who are members of a Section 13(d) group with the Reporting Persons or their affiliates to exceed 9.99% of the total number of issued and outstanding shares of Common Stock of the Issuer following such exercise.

RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund. The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

Held directly by the Fund.

RA Capital Healthcare Fund, L.P. (the "Fund") entered into an Exchange Agreement with the Issuer pursuant to which the Fund exchanged, on a 1:1 basis, 8,500,000 shares of the Issuer's Common Stock for an equal number of prefunded warrants, each to purchase one share of the Issuer's Common Stock at an exercise price of $0.001 per share (each a "Pre-Funded Warrant").

RA Capital Management, L.P. (the "Adviser") is the investment manager for the Fund. The general partner of the Adviser is RA Capital Management GP, LLC (the "Adviser GP"), of which Dr. Peter Kolchinsky and Mr. Rajeev Shah are the managing members. Each of the Adviser, the Adviser GP, the Fund, Dr. Kolchinsky and Mr. Shah disclaims beneficial ownership of any of the reported securities, except to the extent of its or his respective pecuniary interest therein.

Held directly by the Fund.

This transaction involved a cash exercise of a stock option without a subsequent sale of the underlying shares of common stock.

This option was granted on May 12, 2023 and vested 25% on the first anniversary of the vesting commencement date of May 12, 2023. The remainder of the shares underlying the grant shall vest in equal quarterly installments over the following three years until the fourth anniversary of the vesting commencement date, subject to continued service.

This transaction involved a cash exercise of a stock option without a subsequent sale of the underlying shares of common stock.

This option was granted on June 17, 2024 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 17, 2024 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.

This option was granted on June 17, 2024 and is scheduled to vest in equal monthly installments until June 17, 2027, subject to continued service.

This option was granted on June 17, 2024 and is scheduled to vest with respect to all shares on the first anniversary of the grant date or, if earlier, immediately prior to the first annual meeting of stockholders occurring after the grant date, subject to continued service.