Merck KGaA has for the fourth time extended its offer for AZ Electronic Materials. The German chemical and pharmaceuticals company said more additional time is needed to allow the Chinese antitrust authority MOFCOM to review filings. The newest deadline for AZ shareholders to accept the offer is March 14.

Merck said discussions with China's ministry of commerce have "proceeded constructively." Separately, it said antitrust clearance in Japan was granted on Feb. 10. Authorities in Germany, Taiwan and the U.S. have already given the green light.

As of Feb. 28, AZ shareholders had tendered stock worth around 64.03% of the company's existing share capital, Merck said.