LNTH

Consists of 19,001 restricted stock units that vest in equal installments over a three-year period and 19,001 Total Shareholder Return performance-based restricted stock units ("PSUs") that cliff vest following a three-year performance period. The amount of PSUs included in this Report reflects the target award; however, the ultimate award size can range from 0% to 200% of the target based on the actual performance achieved at the end of the performance period.

Consists of 3,079 restricted stock units that vest in equal installments over a three-year period and 3,079 Total Shareholder Return performance-based restricted stock units ("PSUs") that cliff vest following a three-year performance period. The amount of PSUs included in this Report reflects the target award; however, the ultimate award size can range from 0% to 200% of the target based on the actual performance achieved at the end of the performance period.

Consists of 18,346 restricted stock units that vest in equal installments over a three-year period and 18,346 Total Shareholder Return performance-based restricted stock units ("PSUs") that cliff vest following a three-year performance period. The amount of PSUs included in this Report reflects the target award; however, the ultimate award size can range from 0% to 200% of the target based on the actual performance achieved at the end of the performance period.

Consists of 13,104 restricted stock units that vest in equal installments over a three-year period and 13,104 Total Shareholder Return performance-based restricted stock units ("PSUs") that cliff vest following a three-year performance period. The amount of PSUs included in this Report reflects the target award; however, the ultimate award size can range from 0% to 200% of the target based on the actual performance achieved at the end of the performance period.

Consists of 10,483 restricted stock units that vest in equal installments over a three-year period and 10,483 Total Shareholder Return performance-based restricted stock units ("PSUs") that cliff vest following a three-year performance period. The amount of PSUs included in this Report reflects the target award; however, the ultimate award size can range from 0% to 200% of the target based on the actual performance achieved at the end of the performance period.

The transaction reported in this Form 4 reflects additional shares of common stock issued by Lantheus Holdings, Inc. to the reporting person upon the vesting of relative Total Shareholder Return performance-based restricted stock units ("PSUs") that were previously granted and included in the Form 4 filed on March 6, 2023. The number of shares reported in the Form 4 reflected 100% of the target number of shares underlying the PSUs. The number of shares that actually vested under the PSUs equaled 162.8% of the target number of shares. Accordingly, the number of shares reported in this Form 4 reflects the difference between the number of shares that actually vested under the PSUs and the target number of shares originally included in the Form 4.

The transaction reported in this Form 4 reflects additional shares of common stock issued by Lantheus Holdings, Inc. to the reporting person upon the vesting of relative Total Shareholder Return performance-based restricted stock units ("PSUs") that were previously granted and included in the Form 4 filed on March 6, 2023. The number of shares reported in the Form 4 reflected 100% of the target number of shares underlying the PSUs. The number of shares that actually vested under the PSUs equaled 162.8% of the target number of shares. Accordingly, the number of shares reported in this Form 4 reflects the difference between the number of shares that actually vested under the PSUs and the target number of shares originally included in the Form 4.

The transaction reported in this Form 4 reflects additional shares of common stock issued by Lantheus Holdings, Inc. to the reporting person upon the vesting of relative Total Shareholder Return performance-based restricted stock units ("PSUs") that were previously granted and included in the Form 3 filed upon the reporting person becoming a Section 16 officer. The number of shares reported in the Form 3 reflected 100% of the target number of shares underlying the PSUs. The number of shares that actually vested under the PSUs equaled 162.8% of the target number of shares. Accordingly, the number of shares reported in this Form 4 reflects the difference between the number of shares that actually vested under the PSUs and the target number of shares originally included in the Form 3.

The transaction reported in this Form 4 reflects additional shares of common stock issued by Lantheus Holdings, Inc. to the reporting person upon the vesting of relative Total Shareholder Return performance-based restricted stock units ("PSUs") that were previously granted and included in the Form 4 filed on March 6, 2023. The number of shares reported in the Form 4 reflected 100% of the target number of shares underlying the PSUs. The number of shares that actually vested under the PSUs equaled 162.8% of the target number of shares. Accordingly, the number of shares reported in this Form 4 reflects the difference between the number of shares that actually vested under the PSUs and the target number of shares originally included in the Form 4.

Includes 143 shares acquired under the LNTH employee stock purchase plan on March 13, 2025, and 95 shares acquired under the LNTH employee stock purchase plan on September 12, 2025.

The option vests in full on November 17, 2026.

Consists of 14,285 restricted stock units that will vest in full on November 17, 2026.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $56.14 to $56.55, 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 purchased at each separate price within the range.

The entities and individuals identified in the footnotes of this Form 4 may be deemed members of a group holding equity securities of Lantheus Holdings, Inc. (the "Issuer"). The filing of this Form 4 and any statements included herein shall not be deemed to be an admission that such entities and individuals are members of such a group.

Since the number of reporting persons that may be listed on a Form 4 is limited, the entities and individuals listed in these footnotes that are not reporting persons on this Form 4 are filing an additional Form 4 on the date hereof as reporting persons with respect to the securities described herein (the "Parallel Form 4"). Information regarding these entities and individuals is included in this Form 4 for purposes of clarification and convenience only, and is duplicative of the information reported in the Parallel Form 4.

The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

Farallon Partners, L.L.C. and certain affiliated entities (the "Farallon General Partners"), as general partner or sole member of the general partner, as the case may be, of each of the Farallon Funds, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. The Farallon General Partners disclaim any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "'34 Act"), or otherwise, except to the extent of their pecuniary interest, if any.

Each of Joshua J. Dapice, Philip D. Dreyfuss, Hannah E. Dunn, Richard B. Fried, Varun N. Gehani, Nicolas Giauque, David T. Kim, Michael G. Linn, Patrick (Cheng) Luo, Rajiv A. Patel, Thomas G. Roberts, Jr., Edric C. Saito, William Seybold, Daniel S. Short, Andrew J. M. Spokes, John R. Warren, and Mark C. Wehrly (collectively, the "Managing Members"), as a managing member or manager, or senior managing member or senior manager, as the case may be, of each of the Farallon General Partners, in each case with the power to exercise investment discretion, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. Each of the Managing Members disclaims any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the '34 Act or otherwise, except to the extent of his or her pecuniary interest, if any.

The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $56.14 to $56.55, 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 purchased at each separate price within the range.

The entities and individuals identified in the footnotes of this Form 4 may be deemed members of a group holding equity securities of Lantheus Holdings, Inc. (the "Issuer"). The filing of this Form 4 and any statements included herein shall not be deemed to be an admission that such entities and individuals are members of such a group.

Since the number of reporting persons that may be listed on a Form 4 is limited, the entities and individuals listed in these footnotes that are not reporting persons on this Form 4 are filing an additional Form 4 on the date hereof as reporting persons with respect to the securities described herein (the "Parallel Form 4"). Information regarding these entities and individuals is included in this Form 4 for purposes of clarification and convenience only, and is duplicative of the information reported in the Parallel Form 4.

The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

Farallon Partners, L.L.C. and certain affiliated entities (the "Farallon General Partners"), as general partner or sole member of the general partner, as the case may be, of each of the Farallon Funds, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. The Farallon General Partners disclaim any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "'34 Act"), or otherwise, except to the extent of their pecuniary interest, if any.

Each of Joshua J. Dapice, Philip D. Dreyfuss, Hannah E. Dunn, Richard B. Fried, Varun N. Gehani, Nicolas Giauque, David T. Kim, Michael G. Linn, Patrick (Cheng) Luo, Rajiv A. Patel, Thomas G. Roberts, Jr., Edric C. Saito, William Seybold, Daniel S. Short, Andrew J. M. Spokes, John R. Warren, and Mark C. Wehrly (collectively, the "Managing Members"), as a managing member or manager, or senior managing member or senior manager, as the case may be, of each of the Farallon General Partners, in each case with the power to exercise investment discretion, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. Each of the Managing Members disclaims any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the '34 Act or otherwise, except to the extent of his or her pecuniary interest, if any.

The entities and individuals identified in the footnotes of this Form 4 may be deemed members of a group holding equity securities of Lantheus Holdings, Inc. (the "Issuer"). The filing of this Form 4 and any statements included herein shall not be deemed to be an admission that such entities and individuals are members of such a group.

Since the number of reporting persons that may be listed on a Form 4 is limited, the entities and individuals listed in these footnotes that are not reporting persons on this Form 4 are filing an additional Form 4 on the date hereof as reporting persons with respect to the securities described herein (the "Parallel Form 4"). Information regarding these entities and individuals is included in this Form 4 for purposes of clarification and convenience only, and is duplicative of the information reported in the Parallel Form 4.

The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

Farallon Partners, L.L.C. and certain affiliated entities (the "Farallon General Partners"), as general partner or sole member of the general partner, as the case may be, of each of the Farallon Funds, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. The Farallon General Partners disclaim any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "'34 Act"), or otherwise, except to the extent of their pecuniary interest, if any.

Each of Joshua J. Dapice, Philip D. Dreyfuss, Hannah E. Dunn, Richard B. Fried, Varun N. Gehani, Nicolas Giauque, David T. Kim, Michael G. Linn, Patrick (Cheng) Luo, Rajiv A. Patel, Thomas G. Roberts, Jr., Edric C. Saito, William Seybold, Daniel S. Short, Andrew J. M. Spokes, John R. Warren, and Mark C. Wehrly (collectively, the "Managing Members"), as a managing member or manager, or senior managing member or senior manager, as the case may be, of each of the Farallon General Partners, in each case with the power to exercise investment discretion, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. Each of the Managing Members disclaims any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the '34 Act or otherwise, except to the extent of his or her pecuniary interest, if any.

The entities and individuals identified in the footnotes of this Form 4 may be deemed members of a group holding equity securities of Lantheus Holdings, Inc. (the "Issuer"). The filing of this Form 4 and any statements included herein shall not be deemed to be an admission that such entities and individuals are members of such a group.

Since the number of reporting persons that may be listed on a Form 4 is limited, the entities and individuals listed in these footnotes that are not reporting persons on this Form 4 are filing an additional Form 4 on the date hereof as reporting persons with respect to the securities described herein (the "Parallel Form 4"). Information regarding these entities and individuals is included in this Form 4 for purposes of clarification and convenience only, and is duplicative of the information reported in the Parallel Form 4.

The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

Farallon Partners, L.L.C. and certain affiliated entities (the "Farallon General Partners"), as general partner or sole member of the general partner, as the case may be, of each of the Farallon Funds, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. The Farallon General Partners disclaim any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the Securities Exchange Act of 1934, as amended (the "'34 Act"), or otherwise, except to the extent of their pecuniary interest, if any.

Each of Joshua J. Dapice, Philip D. Dreyfuss, Hannah E. Dunn, Richard B. Fried, Varun N. Gehani, Nicolas Giauque, David T. Kim, Michael G. Linn, Patrick (Cheng) Luo, Rajiv A. Patel, Thomas G. Roberts, Jr., Edric C. Saito, William Seybold, Daniel S. Short, Andrew J. M. Spokes, John R. Warren, and Mark C. Wehrly (collectively, the "Managing Members"), as a managing member or manager, or senior managing member or senior manager, as the case may be, of each of the Farallon General Partners, in each case with the power to exercise investment discretion, may be deemed to be a beneficial owner of the Issuer's securities held by the Farallon Funds. Each of the Managing Members disclaims any beneficial ownership of any of the Issuer's securities reported or noted herein for purposes of Section 16 of the '34 Act or otherwise, except to the extent of his or her pecuniary interest, if any.

The option vests in three equal annual installments beginning on August 15, 2026.

Consists of 14,765 restricted stock units that vest in equal installments over a three-year period.

The transaction reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on February 27, 2025.

The transaction reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 6, 2025.

100% of the shares subject to the option are fully vested and exercisable.

The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 7, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $81.984 to $82.977, inclusive. The reporting person undertakes to provide to LNTH, any security holder of LNTH or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (3) to this Form 4.

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

The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 7, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $80.915 to $81.78, inclusive. The reporting person undertakes to provide to Lantheus Holdings, Inc. ("LNTH"), any security holder of LNTH or the staff of the Securities and Exchange Commission ("SEC"), upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (2) to this Form 4.

The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 7, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $82.997 to $83.98, inclusive. The reporting person undertakes to provide to LNTH, any security holder of LNTH or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (4) to this Form 4.

The transaction reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on February 27, 2025.