German pharmaceutical company Merck KGaA says it will buy U.S. biotech equipment maker Millipore Corp. for $6 billion in cash in a move to expand its presence in the life science sector.

The deal, which Merck values at $7.2 billion including assumed debt, ends speculation that has swirled since reports last week said lab instrument maker Thermo Fisher Scientific Inc. made a $6 billion offer for the Billerica, Mass., company.

Merck says it will pay $107 per share in cash — marking a 50 percent premium to Millipore's $71.34 closing stock price on Feb. 19, the last trading day before takeover reports surfaced.