MBIO · Mustang Bio, Inc.

19 shares of common stock were relinquished to cover tax liability associated with the delivery of shares of common stock upon the vesting of restricted stock units.

The Reporting Person is entitled to an annual dividend on its Class A Preferred Stock equal to 2.5% of the Issuer's fully diluted outstanding capitalization on December 31. 278,385 shares were granted by the Issuer to the Reporting person for the 2025 annual dividend.

Represents a private purchase of 247 shares of common stock from another member of the board of directors of the Issuer.

Effective January 15, 2025, the Issuer effected a one-for-fifty reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Effective January 15, 2025, the Issuer effected a one-for-fifty reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Represents a private sale of 247 shares of common stock to another member of the board of directors of the Issuer.

Effective January 15, 2025, the Issuer effected a one-for-fifty reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

The Issuer is required to grant to the Reporting Person an equity fee in shares of the Issuer's Common Stock equal to 2.5% of the gross amount of any debt or equity financing consummated by the Issuer. These shares were granted by the Issuer to the Reporting Person following the receipt of proceeds by the Issuer upon the exercise of warrants previously issued by the Issuer.

27 shares of common stock were relinquished to cover tax liability associated with the delivery of shares of common stock upon the vesting of restricted stock units.

Effective January 15, 2025, the Issuer effected a one-for-fifty reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

The Issuer is required to grant to the Reporting Person an equity fee in shares of the Issuer's Common Stock equal to 2.5% of the gross amount of any debt or equity financing consummated by the Issuer. These shares were granted by the Issuer to the Reporting Person following the receipt of proceeds by the Issuer upon the exercise of warrants previously issued by the Issuer.

The Issuer is required to grant to the Reporting Person an equity fee in shares of the Issuer's Common Stock equal to 2.5% of the gross amount of any debt or equity financing consummated by the Issuer. 575,191 shares were granted by the Issuer to the Reporting Person following the closing of equity financings.

1,396 shares of common stock were relinquished to cover tax liability associated with the delivery of shares of common stock upon the vesting of restricted stock units.

Includes 5,000 shares of common stock acquired under the Mustang Bio, Inc. Employee Stock Purchase Plan on March 1, 2024.

Effective April 3, 2023, the Issuer effected a one-for-fifteen reverse stock split of its common stock (the "Reverse Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Split.

The Issuer is required to grant to the Reporting Person an equity fee in shares of the Issuer's Common Stock equal to 2.5% of the gross amount of any debt or equity financing consummated by the Issuer. 66,003 shares were granted by the Issuer to the Reporting Person following the closing of equity financings.

The Reporting Person is entitled to an annual dividend on its Class A Preferred Stock equal to 2.5% of the Issuer's fully diluted outstanding capitalization on December 31. 353,089 shares were granted by the Issuer to the Reporting Person for the 2023 annual dividend.

The Reporting Person was granted 7,246 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 5, 2023. The shares will vest on July 5, 2026, subject to the Reporting Person's continued service on the Issuer's board on such date.

Effective April 3, 2023, the Issuer effected a fifteen-for-one reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 7,246 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 5, 2023. The shares will vest on July 5, 2026, subject to the Reporting Person's continued service on the Issuer's board on such date.

Effective April 3, 2023, the Issuer effected a fifteen-for-one reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 7,246 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 5, 2023. The shares will vest on July 5, 2026, subject to the Reporting Person's continued service on the Issuer's board on such date.

Effective April 3, 2023, the Issuer effected a fifteen-for-one reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 7,246 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 5, 2023. The shares will vest on July 5, 2026, subject to the Reporting Person's continued service on the Issuer's board on such date.

Effective April 3, 2023, the Issuer effected a fifteen-for-one reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Includes restricted share units, which vest over various time periods.

The shares are held by Caribe BioAdvisors, LLC, of which Mr. Weiss is the sole member.

The Reporting Person was granted 7,246 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 5, 2023. The shares will vest on July 5, 2026, subject to the Reporting Person's continued service on the Issuer's board on such date.

Effective April 3, 2023, the Issuer effected a fifteen-for-one reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Includes restricted share units, which vest over various time periods.

Represents an award of 5,000 restricted stock units that will vest in four annual installments after the grant date, vesting in full on April 24, 2027.

Effective April 3, 2023, the Issuer effected a fifteen-for-one reverse stock split of its common stock (the "Reverse Stock Split"). The amount of common stock reflected on this Form 4 has been adjusted to reflect the Reverse Stock Split.

Includes restricted share units, which vest over various time periods.

1,572 shares of common stock were relinquished to cover tax liability associated with the delivery of shares of common stock upon the vesting of restricted stock units.

The Reporting Person is entitled to an annual dividend on its Class A Preferred Stock equal to 2.5% of the Issuer's fully diluted outstanding capitalization on December 31. These shares were granted by the Issuer to the Reporting Person for the 2022 annual dividend.

The total number of shares beneficially owned by the Reporting Person includes those transactions as disclosed on the table filed herewith as Exhibit 99.

Shares acquired as purchases made under the Issuer's Employee Stock Purchase Plan ("ESPP") during the ESPP offering period.

Includes restricted share units, which vest over various time periods.

Shares acquired as purchases made under the Issuer's Employee Stock Purchase Plan ("ESPP") during the ESPP offering period.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 71,664 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 29, 2022. The shares will vest on June 17, 2025, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 71,664 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 29, 2022. The shares will vest on June 17, 2025, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 71,664 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 29, 2022. The shares will vest on June 17, 2025, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 71,664 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 29, 2022. The shares will vest on June 17, 2025, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The shares are held by Caribe BioAdvisors, LLC, of which Mr. Weiss is the sole member.

The Reporting Person was granted 71,664 restricted shares pursuant to the Issuer's 2016 Incentive Plan on July 29, 2022. The shares will vest on June 17, 2025, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

Represents an award of 61,000 restricted stock units that will vest in four annual installments after the grant date, vesting in full on April 24, 2026.

Includes restricted share units, which vest over various time periods.

1,248 shares of common stock were relinquished to cover tax liability associated with the delivery of shares of common stock upon the vesting of restricted stock units.

The amount of common stock reflected on this Form 4 has been adjusted to reflect a 1-for-15 reverse stock split that occurred subsequent to this transaction.

Includes 3,975 shares of common stock acquired under the Mustang Bio, Inc. Employee Stock Purchase Plan on March 1, 2023 and September 1, 2023.

Shares acquired as purchases made under the Issuer's Employee Stock Purchase Plan ("ESPP") during the ESPP offering period.

Includes restricted share units, which vest over various time periods.

Shares acquired as purchases made under the Issuer's Employee Stock Purchase Plan ("ESPP") during the ESPP offering period.

Includes restricted share units, which vest over various time periods.

4,374 shares were sold in connection with the vesting of 13,750 shares on December 4, 2021, these shares were sold by the Company's restricted stock administrator in order to satisfy Mr. Achenbach's tax withholding obligations. Mr. Achenbach had no discretion with respect to such sale, which was transacted automatically in accordance with the Company's corporate policies regarding the vesting of restricted stock.

Represents the weighted average sales price.

Includes restricted share units, which vest over various time periods.

Each restricted stock unit represents the right to receive one share of Common Stock of Mustang Bio, Inc. The restricted stock units will vest at different times over a period of 4 years.

Includes restricted share units, which vest over various time periods.

Reflects the weighted average purchase price of multiple same-way open market purchase transactions effected by the Reporting Person on the same day at different prices through a purchase order executed by a broker-dealer. The Reporting Person reported on a single line all such transactions that occurred within a one-dollar price range. The range of prices for the purchase transactions on October 27, 2021, was $2.22 to $2.26. The Reporting Person hereby undertakes to provide upon request by the Securities Exchange Commission staff, the Issuer, or a shareholder of the Issuer, full information regarding the number of shares purchased at each separate price.

Includes restricted stock units, which vest over various time periods.

4,450 shares were sold in connection with the vesting of 14,688 shares on October 10, 2021, these shares were sold by the Company's restricted stock administrator in order to satisfy Mr. Achenbach's tax withholding obligations. Mr. Achenbach had no discretion with respect to such sale, which was transacted automatically in accordance with the Company's corporate policies regarding the vesting of restricted stock.

Represents the weighted average sales price.

Includes restricted share units, which vest over various time periods.

These shares were acquired under the Mustang Bio, Inc. Employee Share Purchase Plan ("ESPP") for the ESPP purchase period beginning on March 1, 2021 and ending on August 31, 2021 in transactions that were exempt under both Rule 16b-3(d) and Rule 16b-3(c). In accordance with the terms of the ESPP, these shares were purchased at a price equal to 85% of the fair market value closing price of the Issuer's ordinary shares on August 31, 2021 (the purchase date of the offering period).

Includes restricted shares, which vest over various time periods.

These shares were acquired under the Mustang Bio, Inc. Employee Share Purchase Plan ("ESPP") for the ESPP purchase period beginning on March 1, 2021 and ending on August 31, 2021 in transactions that were exempt under both Rule 16b-3(d) and Rule 16b-3(c). In accordance with the terms of the ESPP, these shares were purchased at a price equal to 85% of the fair market value closing price of the Issuer's ordinary shares on August 31, 2021 (the purchase date of the offering period).

Includes restricted stock units, which vest over various time periods.

Reflects the weighted average purchase price of multiple same-way open market purchase transactions effected by the Reporting Person on the same day at different prices through a purchase order executed by a broker-dealer. The Reporting Person reported on a single line all such transactions that occurred within a one-dollar price range. The range of prices for the purchase transactions on July 30, 2021, was $2.89 to $2.94. The Reporting Person hereby undertakes to provide upon request by the Securities Exchange Commission staff, the Issuer, or a shareholder of the Issuer, full information regarding the number of shares purchased at each separate price.

Includes restricted stock units, which vest over various time periods.

The Reporting Person was granted 13,774 restricted shares pursuant to the Issuer's 2016 Incentive Plan on June 28, 2021. The shares will vest on June 17, 2024, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 13,774 restricted shares pursuant to the Issuer's 2016 Incentive Plan on June 28, 2021. The shares will vest on June 17, 2024, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 13,774 restricted shares pursuant to the Issuer's 2016 Incentive Plan on June 28, 2021. The shares will vest on June 17, 2024, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The Reporting Person was granted 13,774 restricted shares pursuant to the Issuer's 2016 Incentive Plan on June 28, 2021. The shares will vest on June 17, 2024, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

13,774 restricted shares were granted pursuant to the Issuer's 2016 Incentive Plan on June 28, 2021. The shares will vest on June 17, 2024, subject to the Reporting Person's continued service on the Issuer's board on such date.

Includes restricted share units, which vest over various time periods.

The shares are held by Caribe BioAdvisors, LLC, of which Mr. Weiss is the sole member.

Each restricted stock unit represents the right to receive one share of Common Stock of Mustang Bio, Inc. The restricted stock units will vest at different times over a period of 4 years.

Includes restricted stock units, which vest over various time periods.

2,423 shares were sold in connection with the vesting of 8,750 shares on March 27, 2021, these shares were sold by the Company's restricted stock administrator in order to satisfy Mr. Achenbach's tax withholding obligations. Mr. Achenbach had no discretion with respect to such sale, which was transacted automatically in accordance with the Company's corporate policies regarding the vesting of restricted stock.

Represents the weighted average sales price.

Includes restricted share units, which vest over various time periods.

Reflects the weighted average purchase price of multiple same-way open market purchase transactions effected by the Reporting Person on the same day at different prices through a purchase order executed by a broker-dealer. The Reporting Person reported on a single line all such transactions that occurred within a one-dollar price range. The range of prices for the purchase transactions on March 5, 2021, was $3.01 to $3.177. The Reporting Person hereby undertakes to provide upon request by the Securities Exchange Commission staff, the Issuer, or a shareholder of the Issuer, full information regarding the number of shares purchased at each separate price.

Includes restricted share units, which vest over various time periods.

These shares were acquired under the Mustang Bio, Inc. Employee Share Purchase Plan ("ESPP") for the ESPP purchase period beginning on September 1, 2020 and ending on February 28, 2021 in transactions that were exempt under both Rule 16b-3(d) and Rule 16b-3(c). In accordance with the terms of the ESPP, these shares were purchased at a price equal to 85% of the fair market value closing price of the Issuer's ordinary shares on September 1, 2020 (the purchase date of the offering period).

Includes restricted share units, which vest over various time periods.

These shares were acquired under the Mustang Bio, Inc. Employee Share Purchase Plan ("ESPP") for the ESPP purchase period beginning on September 1, 2020 and ending on February 28, 2021 in transactions that were exempt under both Rule 16b-3(d) and Rule 16b-3(c). In accordance with the terms of the ESPP, these shares were purchased at a price equal to 85% of the fair market value closing price of the Issuer's ordinary shares on September 1, 2020 (the purchase date of the offering period).

Includes restricted share units, which vest over various time periods.

Each restricted stock unit represents the right to receive one share of Common Stock of Mustang Bio, Inc..

Includes restricted stock units, which vest over various time periods.

Reflects the weighted average purchase price of multiple same-way open market purchase transactions effected by the Reporting Person on the same day at different prices through a purchase order executed by a broker-dealer. The Reporting Person reported on a single line all such transactions that occurred within a one-dollar price range. The range of prices for the purchase transactions on December 15, 2020, was $2.85 to $2.98. The Reporting Person hereby undertakes to provide upon request by the Securities Exchange Commission staff, the Issuer, or a shareholder of the Issuer, full information regarding the number of shares purchased at each separate price.

Includes restricted share units, which vest over various time periods.