(Adds UnitedHealth's response)

Aug 21 (Reuters) - UnitedHealth Group Inc, Amazon.com Inc, CVS Health Corp and Option Care Health Inc are bidding for Signify Health Inc, Bloomberg News reported on Sunday, citing two people with knowledge of the matter.

UnitedHealth has submitted the highest bid in excess of $30 a share, while Amazon's offer is close behind, Bloomberg said. Signify will hold a board meeting on Monday to discuss the bids, and final bids are expected Sept. 6, Bloomberg said.

The Wall Street Journal had earlier reported that Amazon was bidding for Signify and that it is up for sale in an auction that could value it at well over $8 billion.

The companies did not respond to Reuters' requests for comment on Sunday. Amazon said it does not comment on speculation, while UnitedHealth said it does not comment on rumors and speculation.

Earlier this month, the Wall Street Journal reported CVS was seeking to buy Signify as it looked to expand in-home health services.

Signify has a market cap of around $4.97 billion based on its stock closing price of $21.20 on Friday, data from Refinitiv showed. (Reporting by Juby Babu in Bengaluru; Editing by Christopher Cushing, Deepa Babington and Lincoln Feast.)