LNTH

SEC source: 0002064832-26-000307 · form4.xml · nonDerivative · entry 1

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 122,071

SEC source: 0002064832-26-000278 · form4.xml · nonDerivative · entry 1

Dinkelborg Ludger · CIK 0002082134 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 33,195

SEC source: 0002064832-26-000277 · form4.xml · nonDerivative · entry 1

Brown Kimberly · CIK 0002033488 · Chief Accounting Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,263

SEC source: 0002064832-26-000207 · form4.xml · nonDerivative · entry 1

Pruden Gary J · CIK 0001673416 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 6,674

SEC source: 0002064832-26-000203 · form4.xml · nonDerivative · entry 1

EASTLAND JULIA MARIE · CIK 0001500189 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 8,019

SEC source: 0002064832-26-000211 · form4.xml · nonDerivative · entry 1

McHugh Julie · CIK 0001487179 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 30,099

SEC source: 0002064832-26-000204 · form4.xml · nonDerivative · entry 1

Thrall James H · CIK 0001315048 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 39,881

SEC source: 0002064832-26-000208 · form4.xml · nonDerivative · entry 1

LENO SAM R · CIK 0001238660 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 67,246

SEC source: 0002064832-26-000210 · form4.xml · nonDerivative · entry 1

Morrow Phuong Khanh · CIK 0001928989 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 7,237

SEC source: 0002064832-26-000209 · form4.xml · nonDerivative · entry 1

Maeusli Heinz Christoph · CIK 0001788919 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 30,014

SEC source: 0002064832-26-000206 · form4.xml · nonDerivative · entry 1

Baylor-Henry Minnie · CIK 0001747260 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 14,018

SEC source: 0002064832-26-000205 · form4.xml · nonDerivative · entry 1

Ber Gerard · CIK 0001762144 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 27,499

SEC source: 0002064832-26-000219 · form4.xml · nonDerivative · entry 1

Ber Gerard · CIK 0001762144 · Director

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 27,118

SEC source: 0002064832-26-000218 · form4.xml · nonDerivative · entry 1

Heino Mary Anne · CIK 0001610676 · Director · Executive Chair and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 321,897

SEC source: 0002064832-26-000171 · form4.xml · nonDerivative · entry 1

Niedzwiecki Daniel · CIK 0001861113 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 117,465

SEC source: 0002064832-26-000124 · form4.xml · nonDerivative · entry 1

Dinkelborg Ludger · CIK 0002082134 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 35,731

F1 · kind: 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.

SEC source: 0002064832-26-000122 · form4.xml · nonDerivative · entry 2

Brown Kimberly · CIK 0002033488 · Chief Accounting Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,726

SEC source: 0002064832-26-000122 · form4.xml · nonDerivative · entry 1

Brown Kimberly · CIK 0002033488 · Chief Accounting Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 13,859

F1 · kind: 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.

SEC source: 0002064832-26-000121 · form4.xml · nonDerivative · entry 2

Morgan Amanda Michelle · CIK 0002018026 · Chief Commercial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 64,153

SEC source: 0002064832-26-000121 · form4.xml · nonDerivative · entry 1

Morgan Amanda Michelle · CIK 0002018026 · Chief Commercial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 64,748

F1 · kind: 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.

SEC source: 0002064832-26-000125 · form4.xml · nonDerivative · entry 2

Niedzwiecki Daniel · CIK 0001861113 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 119,376

SEC source: 0002064832-26-000125 · form4.xml · nonDerivative · entry 1

Niedzwiecki Daniel · CIK 0001861113 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 120,659

F1 · kind: 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.

SEC source: 0002064832-26-000123 · form4.xml · nonDerivative · entry 2

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 122,792

SEC source: 0002064832-26-000123 · form4.xml · nonDerivative · entry 1

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 123,974

F1 · kind: 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.

SEC source: 0002064832-26-000112 · form4.xml · nonDerivative · entry 2

Morgan Amanda Michelle · CIK 0002018026 · Chief Commercial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 38,540

SEC source: 0002064832-26-000112 · form4.xml · nonDerivative · entry 1

Morgan Amanda Michelle · CIK 0002018026 · Chief Commercial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 41,876

F1 · kind: 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.

SEC source: 0002064832-26-000113 · form4.xml · nonDerivative · entry 2

Niedzwiecki Daniel · CIK 0001861113 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 83,967

SEC source: 0002064832-26-000113 · form4.xml · nonDerivative · entry 1

Niedzwiecki Daniel · CIK 0001861113 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 92,226

F1 · kind: 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.

SEC source: 0002064832-26-000110 · form4.xml · nonDerivative · entry 2

Heino Mary Anne · CIK 0001610676 · Director · Executive Chair and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 323,124

SEC source: 0002064832-26-000110 · form4.xml · nonDerivative · entry 1

Heino Mary Anne · CIK 0001610676 · Director · Executive Chair and CEO

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 365,040

F1 · kind: 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.

SEC source: 0002064832-26-000111 · form4.xml · nonDerivative · entry 2

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 85,972

SEC source: 0002064832-26-000111 · form4.xml · nonDerivative · entry 1

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 96,624

F1 · kind: 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.

SEC source: 0002064832-25-000088 · form4.xml · nonDerivative · entry 2

Morgan Amanda Michelle · CIK 0002018026 · Chief Commercial Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 39,094

F2 · balance_after: 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.

SEC source: 0002064832-25-000020 · form4.xml · derivative · entry 5

Heino Mary Anne · CIK 0001610676 · Director · Executive Chair

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 26,325

Underlying: Common Stock · 26,325 shares

Expires 2035-11-17

F2 · derivative.exercise_date: The option vests in full on November 17, 2026.

SEC source: 0002064832-25-000020 · form4.xml · nonDerivative · entry 1

Heino Mary Anne · CIK 0001610676 · Director · Executive Chair

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 332,935

F1 · kind: Consists of 14,285 restricted stock units that will vest in full on November 17, 2026.

SEC source: 0001062993-25-015276 · form4.xml · nonDerivative · entry 1

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 88,133

SEC source: 0000908834-25-000269 · form4.xml · nonDerivative · entry 2

PATEL RAJIV A · CIK 0001275110 · Member of a Group Owning 10%

Roberts Thomas G. Jr. · CIK 0001453042 · Member of a Group Owning 10%

Saito Edric C. · CIK 0001960819 · Member of a Group Owning 10%

Seybold William · CIK 0001693980 · Member of a Group Owning 10%

Short Daniel S. · CIK 0001960871 · Member of a Group Owning 10%

Spokes Andrew J M · CIK 0001372968 · Member of a Group Owning 10%

Warren John R. · CIK 0001509711 · Member of a Group Owning 10%

WEHRLY MARK C · CIK 0001245635 · Member of a Group Owning 10%

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 3,477,227

F6 · price: 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.

F1 · ownership.nature: 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.

F2 · ownership.nature: 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.

F3 · ownership.nature: The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

F4 · ownership.nature: 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.

F5 · ownership.nature: 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.

SEC source: 0000908834-25-000268 · form4.xml · nonDerivative · entry 2

FARALLON PARTNERS L L C/CA · CIK 0001040153 · 10% owner · Member of a Group Owning 10%

Dapice Joshua J. · CIK 0001960821 · Member of a Group Owning 10%

Dreyfuss Philip D · CIK 0001693981 · Member of a Group Owning 10%

Dunn Hannah E. · CIK 0001960890 · Member of a Group Owning 10%

FRIED RICHARD B · CIK 0001245637 · Member of a Group Owning 10%

Gehani Varun N · CIK 0001904298 · Member of a Group Owning 10%

Giauque Nicolas · CIK 0001372970 · Member of a Group Owning 10%

Kim David T · CIK 0001595643 · Member of a Group Owning 10%

Linn Michael G · CIK 0001495856 · Member of a Group Owning 10%

Luo Patrick (Cheng) · CIK 0002054041 · Member of a Group Owning 10%

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 3,477,227

F6 · price: 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.

F1 · ownership.nature: 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.

F2 · ownership.nature: 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.

F3 · ownership.nature: The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

F4 · ownership.nature: 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.

F5 · ownership.nature: 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.

SEC source: 0000908834-25-000269 · form4.xml · nonDerivative · entry 1

PATEL RAJIV A · CIK 0001275110 · Member of a Group Owning 10%

Roberts Thomas G. Jr. · CIK 0001453042 · Member of a Group Owning 10%

Saito Edric C. · CIK 0001960819 · Member of a Group Owning 10%

Seybold William · CIK 0001693980 · Member of a Group Owning 10%

Short Daniel S. · CIK 0001960871 · Member of a Group Owning 10%

Spokes Andrew J M · CIK 0001372968 · Member of a Group Owning 10%

Warren John R. · CIK 0001509711 · Member of a Group Owning 10%

WEHRLY MARK C · CIK 0001245635 · Member of a Group Owning 10%

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 6,842,227

F1 · ownership.nature: 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.

F2 · ownership.nature: 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.

F3 · ownership.nature: The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

F4 · ownership.nature: 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.

F5 · ownership.nature: 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.

SEC source: 0000908834-25-000268 · form4.xml · nonDerivative · entry 1

FARALLON PARTNERS L L C/CA · CIK 0001040153 · 10% owner · Member of a Group Owning 10%

Dapice Joshua J. · CIK 0001960821 · Member of a Group Owning 10%

Dreyfuss Philip D · CIK 0001693981 · Member of a Group Owning 10%

Dunn Hannah E. · CIK 0001960890 · Member of a Group Owning 10%

FRIED RICHARD B · CIK 0001245637 · Member of a Group Owning 10%

Gehani Varun N · CIK 0001904298 · Member of a Group Owning 10%

Giauque Nicolas · CIK 0001372970 · Member of a Group Owning 10%

Kim David T · CIK 0001595643 · Member of a Group Owning 10%

Linn Michael G · CIK 0001495856 · Member of a Group Owning 10%

Luo Patrick (Cheng) · CIK 0002054041 · Member of a Group Owning 10%

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: No plan indicated

Ownership: Indirect · See Footnotes

Disclosed balance after: 6,842,227

F1 · ownership.nature: 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.

F2 · ownership.nature: 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.

F3 · ownership.nature: The amount of securities shown in this row is held directly by certain investment funds affiliated with the reporting persons (the "Farallon Funds").

F4 · ownership.nature: 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.

F5 · ownership.nature: 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.

SEC source: 0001062993-25-014678 · form4.xml · derivative · entry 2

Dinkelborg Ludger · CIK 0002082134 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 25,324

Underlying: Common Stock · 25,324 shares

Expires 2035-08-15

F2 · derivative.exercise_date: The option vests in three equal annual installments beginning on August 15, 2026.

SEC source: 0001062993-25-014678 · form4.xml · nonDerivative · entry 1

Dinkelborg Ludger · CIK 0002082134 · See Remarks

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 14,765

F1 · kind: Consists of 14,765 restricted stock units that vest in equal installments over a three-year period.

SEC source: 0001062993-25-014679 · form4.xml · nonDerivative · entry 1

Brown Kimberly · CIK 0002033488 · Chief Accounting Officer

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 7,701

SEC source: 0001062993-25-014521 · form4.xml · nonDerivative · entry 1

Blanchfield Paul · CIK 0001801395 · President

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 108,214

F1 · kind: 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.

SEC source: 0001062993-25-012955 · form4.xml · nonDerivative · entry 1

Blanchfield Paul · CIK 0001801395 · President

10b5-1 filing: No plan indicated

Ownership: Direct

Disclosed balance after: 111,274

SEC source: 0001062993-25-011827 · form4.xml · nonDerivative · entry 1

Niedzwiecki Daniel · CIK 0001861113 · See Remarks

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 87,057

F1 · kind: 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.

SEC source: 0001062993-25-011413 · form4.xml · nonDerivative · entry 1

McHugh Julie · CIK 0001487179 · Director

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 25,962

F1 · kind: 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.

SEC source: 0001062993-25-011412 · form4.xml · derivative · entry 5

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 14,773 shares

Expires 2032-03-03

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_date: 100% of the shares subject to the option are fully vested and exercisable.

SEC source: 0001062993-25-011412 · form4.xml · nonDerivative · entry 4

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 88,860

F1 · kind: 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.

F4 · price: 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.

SEC source: 0001062993-25-011412 · form4.xml · nonDerivative · entry 3

Marshall Robert J. Jr. · CIK 0001754976 · CFO and Treasurer

10b5-1 filing: Plan reported

Ownership: Direct

Disclosed balance after: 115,896

F1 · kind: 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.

F3 · price: 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.