Royal Philips Electronics has extended its share tender offer for the second time in its planned acquisition of Respironics, Inc. because the European Union (EU) has not completed its antitrust review. The new tender offer will expire on March 6, rather than the previous deadline of February 22.

Respironics was supposed to be acquired by Royal Philips on December 21, with the companies agreeing that the $5.1 billion deal would be done by the first quarter. The deal received antitrust clearance from US regulators at the end of January.

It is unclear why the multinational regulator is still studying the deal, but Respironics' Chief Financial Officer Dan Bevevino said that it was not out of the ordinary that the EU was taking its time. The new expected acquisition date is March 31.