X0508 4 2026-02-19 0 0001356576 SUPERNUS PHARMACEUTICALS, INC. SUPN 0001899935 Sensenig Bethany C/O SUPERNUS PHARMACEUTICALS, INC. 9715 KEY WEST AVENUE ROCKVILLE MD 20850 1 0 0 0 1 Common Stock 2026-02-19 4 M 0 4475 0 A 4475 D Common Stock 2026-02-19 4 S 0 1217 50.31 D 3258 D Common Stock 2026-02-19 4 S 0 3258 51.27 D 0 D Restricted Stock Unit 2026-02-19 4 M 0 4475 0 D Common Stock 4475 0 D Transaction made pursuant to a 10b5-1 trading plan adopted May 15, 2025. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $49.83 to $50.71. The Reporting Person undertakes to provide to Supernus Pharmaceuticals, Inc. ("Supernus"), any security holder of Supernus, 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 range set forth in this footnote 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 $50.98 to $51.56. The Reporting Person undertakes to provide to Supernus, any security holder of Supernus, 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 range set forth in this footnote to this Form 4. Each restricted stock unit represents the right to receive one share of Supernus common stock upon vesting. These restricted stock units were settled in common stock upon vesting, which occurred on February 19, 2026. /s/ Timothy C. Dec, as attorney-in-fact 2026-02-23