Advanced Semiconductor Engineering (ASE) might fail to gain a controlling stake in Siliconware Precision Industries (SPIL), if it cannot win antitrust approval in Taiwan by the deadline of its tender offer for another 24.71% stake in the fellow packaging and testing company.

ASE, which already owns 25% of SPIL, has extended the deadline of its bid for more SPIL shares to March 17. If it cannot receive regulatory approval by that time, the bid will fail since ASE is not allowed to extend the offer period for a second time.

Taiwan law would also forbid ASE from making another bid for SPIL shares within one year after the failure of its most-recent tender offer on the company. Nevertheless, there may be exceptions.

Given that the FTC has extended its review period on the proposal submitted by ASE for up to 60 days, there is a chance that ASE may secure approval by May, said Securities and Futures Bureau Deputy Director-General Chang Li-chen. ASE could use this as a pretext to make another tender offer on SPIL, Chang noted.