X0508 4 2025-11-14 0001069878 TREX CO INC TREX 0001791227 Gandhi Prithvi C/O TREX COMPANY, INC. 2500 TREX WAY WINCHESTER VA 22601 1 SVP, Chief Financial Officer 0 Common Stock 2025-11-14 4 P 0 15000 31.9227 A 30664 D The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $31.835 to $31.93, inclusive. The reporting person undertakes to provide to Issuer, any security holder of 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 ranges set forth in footnote (1) to this Form 4. /s/ Amy M. Fernandez by power of attorney 2025-11-17