LXEO · Lexeo Therapeutics, Inc.

Represents a sale to cover tax obligations on the release of performance Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $4.35 to $4.73. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 100,621 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of performance Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $4.341 to $4.73. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 49,500 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of performance Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $4.33 to $4.73. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 89,665 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of performance Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $4.3402 to $4.7507. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 252,130 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

100% of the shares underlying the option shall vest, and become exercisable, on the earlier of one year following the grant date or the next annual meeting of stockholders, subject to the Reporting Person's continuous service on such date.

100% of the shares underlying the option shall vest, and become exercisable, on the earlier of one year following the grant date or the next annual meeting of stockholders, subject to the Reporting Person's continuous service on such date.

100% of the shares underlying the option shall vest, and become exercisable, on the earlier of one year following the grant date or the next annual meeting of stockholders, subject to the Reporting Person's continuous service on such date.

100% of the shares underlying the option shall vest, and become exercisable, on the earlier of one year following the grant date or the next annual meeting of stockholders, subject to the Reporting Person's continuous service on such date.

100% of the shares underlying the option shall vest, and become exercisable, on the earlier of one year following the grant date or the next annual meeting of stockholders, subject to the Reporting Person's continuous service on such date.

100% of the shares underlying the option shall vest, and become exercisable, on the earlier of one year following the grant date or the next annual meeting of stockholders, subject to the Reporting Person's continuous service on such date.

100% of the shares underlying the option shall vest, and become exercisable, on the earlier of one year following the grant date or the next annual meeting of stockholders, subject to the Reporting Person's continuous service on such date.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $5.06 to $5.11. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 100,621 Restricted Stock Units.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $5.03 to $5.11. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 252,130 Restricted Stock Units.

The shares subject to the option shall vest and become exercisable in equal annual installments over a three year period such that the option is fully vested on the third anniversary of the date of grant, subject to the Reporting Person's continuous service.

The sales in this Form 4 were made pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on November 13, 2025.

This transaction was executed in multiple trades at prices ranging from $5.56 to $5.94. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 261,349 Restricted Stock Units (RSU's). Each RSU represents a contingent right to receive one share of Common Stock, subject to the applicable vesting schedule and conditions of each RSU.

The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the Lexeo Therapeutics, Inc. 2023 Employee Stock Purchase Plan. This transaction is exempt under both Rule 16b-3(c) and Rule 16b-3(d).

Includes 261,349 Restricted Stock Units.

The reporting person is voluntarily reporting the acquisition of shares of the Issuer's common stock pursuant to the Lexeo Therapeutics, Inc. 2023 Employee Stock Purchase Plan. This transaction is exempt under both Rule 16b-3(c) and Rule 16b-3(d).

Includes 104,216 restricted stock units.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $6.22 to $6.47. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 104,216 Restricted Stock Units.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $6.22 to $6.50. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 261,349 Restricted Stock Units.

25% of the shares underlying the option vest and become exercisable on January 20, 2027, and 1/48th of the shares underlying the option shall vest in monthly installments thereafter, subject to the Reporting Person's continuous service.

The reported securities are restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. Twenty-five percent (25%) of the RSUs shall vest on February 15, 2027, and 1/16th of the RSUs shall vest in quarterly installments thereafter on the Issuer's standard quarterly vesting dates, subject to the Reporting Person's continued service through each applicable vesting date.

Includes 49,500 RSUs.

25% of the shares underlying the option vest and become exercisable on February 4, 2027, and 1/48th of the shares underlying the option shall vest in monthly installments thereafter, subject to the Reporting Person's continuous service.

The reported securities are restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. Twenty-five percent (25%) of the RSUs shall vest on February 15, 2027, and 1/16th of the RSUs shall vest in quarterly installments thereafter on the Issuer's standard quarterly vesting dates, subject to the Reporting Person's continued service through each applicable vesting date.

The reported securities are RSUs.

25% of the shares underlying the option vest and become exercisable on February 4, 2027, and 1/48th of the shares underlying the option shall vest in monthly installments thereafter, subject to the Reporting Person's continuous service.

The reported securities are restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. Twenty-five percent (25%) of the RSUs shall vest on February 15, 2027, and 1/16th of the RSUs shall vest in quarterly installments thereafter on the Issuer's standard quarterly vesting dates, subject to the Reporting Person's continued service through each applicable vesting date.

Includes 112,733 RSUs.

The reported securities are restricted stock units ("RSUs"). Each RSU represents a contingent right to receive one share of Common Stock of the Issuer. Twenty-five percent (25%) of the RSUs shall vest on February 15, 2027, and 1/16th of the RSUs shall vest in quarterly installments thereafter on the Issuer's standard quarterly vesting dates, subject to the Reporting Person's continued service through each applicable vesting date.

Includes 290,022 RSUs.

25% of the shares underlying the option vest and become exercisable on February 4, 2027, and 1/48th of the shares underlying the option shall vest in monthly installments thereafter, subject to the Reporting Person's continuous service.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.09 to $9.37. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 48,098 RSUs.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.09 to $9.37. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 128,357 Restricted Stock Units.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.09 to $9.37. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 58,866 RSUs.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.09 to $9.37. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 49,607 RSUs.

On November 20, 2025, the reporting person filed a Form 4 which inadvertently reported that a sale to cover tax obligations occurred on August 18, 2025. In fact, as reported in this amendment, the sale occurred on November 18, 2025.

Represents a sale to cover tax obligations on the release of restricted stock units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.09 to $9.37. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 47,733 RSUs.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.53 to $9.59. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 49,138 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $8.53 to $9.52. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $8.53 to $9.52. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.53 to $9.59. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 60,546 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.53 to $9.59. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 51,092 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.53 to $9.59. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 131,092 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $9.53 to $9.59. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Includes 49,687 RSUs. Each RSU represents a contingent right to receive one share of Common Stock of the Issuer.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $8.53 to $9.52. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $8.53 to $9.52. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.

Represents a sale to cover tax obligations on the release of Restricted Stock Units ("RSUs").

This transaction was executed in multiple trades at prices ranging from $8.53 to $9.52. The price reported above reflects the weighted average sale price. The Reporting Person 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 sale price.