Advanced Semiconductor Engineering (ASE) will be unable to win antitrust approval in Taiwan by March 17 - the deadline of its tender offer for another 24.71% stake in Siliconware Precision Industries (SPIL).

The back-end semiconductor service provider, which already owns 25% of SPIL through a previous tender offer, in December 2015 launched another tender offer aiming to increase its stake in the competitor to almost 50%.

ASE's bid, which expires today, must receive approval by Taiwan's Fair Trade Commission (FTC), but a review by the FTC on Wednesday failed to make a final decision. It means ASE will not obtain regulatory approval by the deadline although the FTC said it will continue to review the case.

The original deadline for the ASE's bid was February 16, but has been extended to March 17 upon ASE's request. ASE is not allowed to extend the offer period for a second time.

Taiwan's law will also forbid ASE from making another tender offer within one year after its failure to meet the regulations.

Following the FTC's failure to reach a decision on Wednesday, SPIL urged the authority to terminate the review, as there is no point continuing it.

ASE's shares closed at NT$35.85 (US$1.09) on the Taiwan Stock Exchange (TSE) on March 16, down NT$0.35 or about 1%, while SPIL's share price closed at NT$50.90, up NT$0.20 or 0.4%.