Taiwan stocks erased early gains and ended flat on Monday, as rises in plastics counters were offset by losses in biotech shares and HTC. The main TAIEX index slipped 1.03 points to 7,129.04, after opening flat. Electronics shares fell 0.4 percent, with HTC off 2 percent. Financial shares gained 0.5 percent. The Taiwan dollar traded up T$0.127 at T$29.145. Foreign investors were net sellers on Friday, bringing their total selling to T$10.33 billion this month.