DaVita Inc. (DVA) shares surged in premarket trading Wednesday, Dec. 6, after UnitedHealth Group Inc. (UNH) said it will pay just under $5 billion for DaVita's medical unit and combine it with its Optum division as it expands into ambulatory care delivery systems.

Optum will pair with DaVita in a deal that adds to its 1.7 million patient base and 300 medical clinics that feature primary and specialist care. OptumCare has around 80 health plans that work through 30,000 affiliated physicians. The deal is valued and $4.9 billion and will be paid in cash.

"Following this transaction, DaVita will continue to be a leader in population health management, with a focus on our U.S. and international kidney care businesses," said Davita CEO Kent Thiry. "We also expect to pursue other investments in health care services outside of kidney care."

"Combining DaVita Medical Group and Optum advances our shared goal of supporting physicians in delivering exceptional patient care in innovative and efficient ways while working with more than 300 health care payers across Optum in ways that better meet the needs of their members," said Optum CEO Larry C. Renfro.

DaVita shares were marked 12.3% higher in premarket dealing in New York, indicating an opening price of $68.25, the highest since May 2. UnitedHealth Group shares traded modestly higher with an indicated opening price of $220.20, a move that would extend their three-month gain to 10.5%.

The deal is just the latest in unusual healthcare combinations. CVS Health (CVS) this week said it will pay $69 billion to buy Aetna (AET) in an effort to offer more complete healthcare solutions to consumers. 

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