X0303 4 2011-02-15 0001069878 TREX CO INC TREX 0001201351 KAPLAN RONALD W C/O TREX COMPANY, INC. 160 EXETER DRIVE WINCHESTER VA 22603-8605 1 1 President and CEO Common Stock 2011-02-15 4 S 0 100 26.08 D 132743 D Common Stock 2011-02-15 4 S 0 1800 26.06 D 130943 D Common Stock 2011-02-15 4 S 0 200 26.055 D 130743 D Common Stock 2011-02-15 4 S 0 600 26.0525 D 130143 D Common Stock 2011-02-15 4 S 0 400 26.05 D 129743 D Common Stock 2011-02-15 4 S 0 200 26.035 D 129543 D Common Stock 2011-02-15 4 S 0 1500 26.03 D 128043 D Common Stock 2011-02-15 4 S 0 100 26.025 D 127943 D Common Stock 2011-02-15 4 S 0 100 26.02 D 127843 D Common Stock 2011-02-15 4 S 0 15000 26.00 D 112843 D Common Stock 2011-02-15 4 F 0 19472 26.00 D 93371 D Common Stock 2011-02-15 4 D 0 23714 26.00 D 69657 D Common Stock 2011-02-16 4 S 0 100 26.12 D 69557 D Common Stock 2011-02-16 4 S 0 200 26.08 D 69357 D Common Stock 2011-02-16 4 S 0 100 26.075 D 69257 D Common Stock 2011-02-16 4 S 0 100 26.07 D 69157 D Common Stock 2011-02-16 4 S 0 100 26.068 D 69057 D Common Stock 2011-02-16 4 S 0 200 26.065 D 68857 D Common Stock 2011-02-16 4 S 0 400 26.06 D 68457 D Common Stock 2011-02-16 4 S 0 100 26.055 D 68357 D Common Stock 2011-02-16 4 S 0 100 26.055 D 68257 D Common Stock 2011-02-16 4 S 0 100 26.05 D 68157 D Common Stock 2011-02-16 4 S 0 1 26.035 D 68156 D Common Stock 2011-02-16 4 S 0 100 26.03 D 68056 D Common Stock 2011-02-16 4 S 0 594 26.02 D 67462 D Common Stock 2011-02-15 4 M 0 70065 8.80 A 137527 D Stock Appreciation Right 8.80 2011-02-15 4 M 0 70065 0 D 2009-01-07 2018-01-07 Common Stock 70065 113662 D The stock appreciation right becomes exerciseable in three equal installments beginning on the first anniversary date of the transaction date. 70,065 Stock Appreciation Rights (SARs) are being exercised pursuant to Rule 10b5-1 trading plan adopted by the reporting person on May 10, 2010. The sales reported in this Form 4 were effected pursuant to Rule 10b5-1 trading plan adopted by the reporting person on May 10, 2010. 19,472 shares are being surrendered to cover payment of taxes currently due on the exercise of SARs, pursuant to Rule 10b5-1 trading plan. /s/ William R. Gupp by power of attorney 2011-02-17