Taiwan stocks fell 0.6 percent to its lowest closing level in 13 weeks on Monday, trailing regional bourses, as smartphone maker HTC Corp tumbled by the maximum allowed in a session after it forecast a fall in revenue in the current quarter. The main TAIEX index finished 42.39 points down at 7,091.67, its lowest close since July 26. HTC dropped 7 percent to T$219.50. The Taiwan dollar was up slightly to stand at T$29.258. Foreign investors were net sellers on Friday, bringing their total selling to T$32.3 billion this month.