Cigna said Sunday it had rejected a multibillion-dollar buyout deal from rival health care giant Anthem, saying it was "deeply disappointed" in the group's actions. The board was unanimous in its decision, calling the offer "inadequate" in a letter to Anthem, which had estimated the deal at $53.8 billion including debt when it made it public Saturday. Cigna had previously rejected an offer exceeding $45 billion from Anthem. It also listed "a number of major issues," including Anthem's lack of a growth strategy. Anthem, the second biggest US health care company after UnitedHealth Group, had revenues of $73.8 billion in 2014 and works as the licensee for Blue Cross and Blue Shield plans in several US states.