Merck KgA has revealed that it has been acquiring shares of Schering AG, pushing its stake in the company near 20%, even as Bayer's deadline to acquire Schering closes in.

Merck previously bid to acquire Schering, but was trumped by Bayer's $21.5 billion offer for that company. As part of that offer, Bayer began acquiring shares in Schering. The company needs 75% of shareholders to vote in favor of the takeover at a June 14 meeting. Bayer currently owns 61.5% of Schering shares, but that number is changing by the hour.

Merck bid 77 euros per share with its March offer, while Bayer proposed 86 euros per share. Schering is currently trading at 86 euros per share