Stocks fell yesterday, with steel, flat-panel display and transportation shares leading the decline.
The TAIEX closed down 15.74 points, or 0.26 percent, at 6,145.92, in dealings valued at NT$101.9 billion (US$3.26 billion).
Decliners outnumbered advancers 499 to 347, while 155 issues ended the day unchanged. The decline came after the benchmark index had risen 2.5 percent so far this month, analysts said.
Steel stocks fell 1.2 percent as a whole, after a Chinese-language newspaper said several steel makers will likely report losses this month and next, analysts said.
"Profit-taking was [the factor] behind the market failing to sustain early gains and being pulled down to negative territory towards the close," said Alvin Teng (鄧可欣), an assistant vice president at SinoPac Securities Corp (建華證券).
The expansion in market turnover suggests that quite a few investors may be "straddled with loss-making positions built earlier in the session," he said.
China Steel Corp (中鋼) fell 1.1 percent to NT$30.90, while Chien Shing Stainless Steel (千興) dropped 3.1 percent to NT$6.93.
Shares of thin-film-transistor liquid-crystal-display makers were mixed despite a strong opening, analysts said.
Chi Mei Optoelectronics Corp (奇美電子), the nation's second largest panel maker, finished the session unchanged at NT$49.40, off its morning high of NT$51. AU Optronics Corp (友達光電) lost 0.2 percent to NT$52.10.
BenQ Corp (明基電通) was down 2.96 percent at NT$31.15, extending the decline of the previous day.