X0609 4 2026-08-31 0000728387 Perspective Therapeutics, Inc. CATX 0002010224 Lantheus Alpha Therapy, LLC false C/O LANTHEUS HOLDINGS, INC. 201 BURLINGTON ROAD, SOUTH BUILDING BEDFORD MA 01730 0 0 1 0 0 Common Stock 2026-08-31 4 S 0 78145 3.143 D 11599194 D Common Stock 2026-09-01 4 S 0 35769 3.1193 D 11563425 D Effective June 14, 2024, Perspective Therapeutics, Inc. ("CATX") effected a 1-for-10 reverse stock split of its common stock (the "Reverse Stock Split"). The amount of securities reported on this Form 4 has been adjusted to reflect the Reverse Stock Split. These sales were previously reported in Form 4s filed by Lantheus Holdings, Inc. on September 2, 2026 and September 3, 2026. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.095 to $3.165, inclusive. The reporting person undertakes to provide to CATX, any security holder of CATX 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 price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $3.08 to $3.165, inclusive. The reporting person undertakes to provide to CATX, any security holder of CATX 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. Represents securities directly held by Lantheus Alpha Therapy, LLC ("Lantheus"), a wholly owned indirect subsidiary of Lantheus Holdings, Inc. ("Lantheus Holdings"). Under SEC rules and regulations, Lantheus Holdings may be deemed to have indirect beneficial ownership of the shares held by Lantheus, which has direct beneficial ownership. /s/ Eric M. Green, Assistant Corporate Secretary 2026-09-04