Stocks Soar on UBS Upgrade: Sunnova Energy, Cal-Maine Foods, Marathon Petroleum & Fluor Corporation Lead the Wa Biggest Stock Movers Midday Sunnova Energy (NOVA): Shares of Sunnova Energy rose 4.3% after the company announced its plans to acquire Vivint Solar in a deal worth $3.2 billion. Cal-Maine Foods (CALM): Shares of Cal-Maine Foods rose 3.2%…