X0306 4 2017-08-14 1 0001521036 Lantheus Holdings, Inc. LNTH 0001374781 Avista Capital Partners GP, LLC AVISTA CAPITAL HOLDINGS, L.P. 65 E. 55TH STREET, 18TH FLOOR NEW YORK NY 10022 0 0 1 0 0001374541 Avista Capital Partners, L.P. 65 EAST 55TH STREET 18TH FLOOR NEW YORK NY 10022 0 0 1 0 0001374540 Avista Capital Partners (Offshore), L.P. 65 EAST 55TH STREET 18TH FLOOR NEW YORK NY 10022 0 0 1 0 0001613694 ACP-Lantern Co-Invest, LLC 65 EAST 55TH STREET 18TH FLOOR NEW YORK NY 10022 0 0 1 0 Common Stock 2017-08-14 4 S 0 64646 17.29 D 3521192 I See footnote Common Stock 2017-08-14 4 S 0 11012 18.05 D 3510180 I See footnote Common Stock 2017-08-14 4 S 0 10493 17.29 D 935060 I See footnote Common Stock 2017-08-14 4 S 0 1788 18.05 D 933272 I See footnote Common Stock 2017-08-14 4 J 0 2785709 17.15 D 724471 I See footnotes Common Stock 2017-08-14 4 J 0 815672 17.15 D 117600 I See footnotes Common Stock 2017-08-14 4 J 0 1762208 17.15 D 0 I See footnote Common Stock 2017-08-15 4 S 0 35084 17.06 D 765045 I See footnote Common Stock 2017-08-15 4 S 0 5695 17.06 D 124186 I See footnote Common Stock 2017-08-16 4 S 0 10434 17.05 D 754611 I See footnote Common Stock 2017-08-16 4 S 0 1694 17.05 D 122492 I See footnote The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.00 to $17.98, inclusive. The Reporting Person undertakes to provide to Lantheus Holdings, Inc., any security holder of Lantheus Holdings, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (1), (2), (8) and (9) to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $18.00 to $18.18, inclusive. Represents shares of the Issuer held by Avista Capital Partners, L.P. ("ACP"). Avista Capital Partners GP, LLC ("ACP GP") is the general partner of ACP. By virtue of this relationship, ACP GP may be deemed to share voting and dispositive power with respect to the shares of common stock held by ACP. Each of ACP GP and ACP expressly disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. Represents shares of the Issuer held by Avista Capital Partners (Offshore), L.P. ("ACP Offshore"). ACP GP is the general partner of ACP Offshore. By virtue of this relationship, ACP GP may be deemed to share voting and dispositive power with respect to the shares of common stock held by ACP Offshore. Each of ACP GP and ACP Offshore expressly disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. On August 14, 2017, ACP distributed 2,785,709 shares of common stock to one or more members or partners. On August 14, 2017, ACP Offshore distributed 815,672 shares of common stock to one or more members or partners. Represents shares of the Issuer held by ACP-Lantern Co-Invest, LLC ("ACP Co-Invest"). ACP GP is the manager of ACP Co-Invest. By virtue of this relationship, ACP GP may be deemed to share voting and dispositive power with respect to the shares of common stock held by ACP Co-Invest. Each of ACP GP and ACP Co-Invest expressly disclaims beneficial ownership of any such securities, except to the extent of its pecuniary interest therein. On August 14, 2017, ACP Co-Invest distributed 1,762,208 shares of common stock to one or more members or partners. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.00 to $17.45, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $17.00 to $17.20, inclusive. Avista Capital Partners GP, LLC, By: /s/ John Cafasso 2017-08-16 Avista Capital Partners, L.P., By: Avista Capital Partners GP, LLC, its General Partner, By: /s/ John Cafasso 2017-08-16 Avista Capital Partners (Offshore), L.P., By: Avista Capital Partners GP, LLC, its General Partner, By: /s/ John Cafasso 2017-08-16 ACP-Lantern Co-Invest, LLC, By: Avista Capital Partners GP, LLC, its Manager, By: /s/ John Cafasso 2017-08-16