Stocks jumped off to modest gains in mixed trade early Wednesday. The S&P 500 led with a 0.4% advance. The Dow Jones industrial average climbed 0.3% and the Nasdaq added 0.1%. Volume rose 20% on the Nasdaq and dipped 4% on the NYSE. The stock market today received at least some boost from Tuesday’s election results, which propelled Republicans into control of the Senate for the first time since 2007 and expanded their control in the House.