CRBU · Caribou Biosciences, Inc.

Reflects the number of shares of common stock that were sold in a "sell-to-cover" transaction for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted prior to the 2023 amendments to Rule 10b5-1. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs.

Reflects the number of shares of common stock that were sold pursuant to the Issuer's mandatory sell-to-cover policy for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person.

Reflects the number of shares of common stock that were sold in a "sell-to-cover" transaction for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted by the reporting person on August 12, 2024. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs.

Reflects the number of shares of common stock that were sold in a "sell-to-cover" transaction for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted prior to the 2023 amendments to Rule 10b5-1. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

1/48 of the total number of shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2030, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2027, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

This transaction was executed in multiple trades on 3/14/2025 at prices ranging from $1.00 to $1.03 per share, inclusive. The price reported above reflects the weighted average purchase price. The reporting person hereby undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares purchased at each separate price within the specified range.

Shares are held by The City Canyon Family Trust dated May 31, 2021, of which the Reporting Person is a Co-Trustee with her spouse.

Reflects the number of shares of common stock that were sold in a "sell to cover" transaction for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted prior to the 2023 amendments to Rule 10b5-1. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs.

This transaction was executed in multiple trades on 2/21/2025 at prices ranging from $1.32 to $1.35. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price within the specified range.

Reflects the number of shares of common stock that were sold in a "sell to cover" transaction for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted prior to the 2023 amendments to Rule 10b5-1. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs.

This transaction was executed in multiple trades on 2/21/2025 at prices ranging from $1.32 to $1.35. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price within the specified range.

Reflects the number of shares of common stock that were sold in a "sell to cover" transaction for the sole purpose of satisfying tax withholding obligations in connection with the vesting of RSUs previously granted to the reporting person and does not represent a discretionary trade by the reporting person. This transaction was made pursuant to a Rule 10b5-1 trading plan in the form of a durable sell-to-cover instruction adopted prior to the 2023 amendments to Rule 10b5-1. The trading plan provides for the automatic sale of shares of common stock necessary to satisfy the reporting person's tax withholding obligations incurred in connection with the vesting of RSUs.

This transaction was executed in multiple trades on 2/21/2025 at prices ranging from $1.32 to $1.35. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request by the staff of the Securities and Exchange Commission, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price within the specified range.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2026, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2026, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2026, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2026, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2026, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2026, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

Includes 10,583 shares purchased pursuant to the Issuer's 2021 Employee Stock Purchase Plan on February 15, 2025.

25% of the options will vest upon the one-year anniversary of the grant date, February 20, 2026, and 1/48th will vest monthly thereafter over the 36-month period following the one-year cliff, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2026, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2026, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2026, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

25% of the options will vest upon the one-year anniversary of the grant date, February 20, 2026, and 1/48th will vest monthly thereafter over the 36-month period following the one-year cliff, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.

25% of the options will vest upon the one-year anniversary of the grant date, February 20, 2026, and 1/48th will vest monthly thereafter over the 36-month period following the one-year cliff, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.

One-twelfth of the shares subject to this option will vest on each monthly anniversary of the grant date such that the option will be fully vested on February 20, 2026, subject to the reporting person continuing to provide service to the Issuer through each such vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2026, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

25% of the options will vest upon the one-year anniversary of the grant date, February 20, 2026, and 1/48th will vest monthly thereafter over the 36-month period following the one-year cliff, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2026, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

This reflects restricted stock units ("RSUs") that vest in four equal annual installments beginning on February 20, 2026, subject to the reporting person's continued services to the Issuer through the applicable vesting dates. The RSUs will be settled in stock within 30 days after each vesting date.

25% of the options will vest upon the one-year anniversary of the grant date, February 20, 2026, and 1/48th will vest monthly thereafter over the 36-month period following the one-year cliff, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.

25% of the options will vest upon the one-year anniversary of the grant date, February 20, 2026, and 1/48th will vest monthly thereafter over the 36-month period following the one-year cliff, subject to the reporting person's continued service to the Issuer through the applicable vesting dates.

25% of the shares subject to the option shall vest on January 2, 2026, and the remaining shares subject to the option shall vest monthly thereafter (1/48 of the shares per month for the 36 months following January 2, 2026), subject to the Reporting Person's continued service to the Issuer through the applicable vesting dates.