Advanced Semiconductor Engineering (ASE) and Siliconware Precision Industries (SPIL) now expect to start the execution of a joint share-exchange MoU reached between the two companies in May by June 30, 2016 instead of the previously-agreed June 25, as the pair are still negotiating, according to the companies.

The pair have signed a supplemental agreement to the MoU under which a new holding company will be formed to hold 100% equity interests in both ASE and SPIL. The companies expect to "complete related negotiations on a best-effort basis and execute the joint share exchange agreement on or before June 30."

Under the terms of the deal reached on May 26, each ASE share will be swapped for 0.5 shares of the holding company, while the holding company will pay NT$55 (US$1.69) in cash per SPIL share. ASE and SPIL will become parallel sibling companies under the new entity while maintaining their separate legal entity status and independent operations.