Stocks remained up sharply but a little off their session highs at midafternoon Wednesday, as investors cheered a federal budget deal that has averted the fiscal cliff. The Nasdaq was up 2.4% after jumping nearly 2.9%. The S&P 500 gained 1.8%, while the Dow Jones industrial average tacked on 1.7%. Volume continued to track up significantly across the board. On Assignment (ASGN) climbed 8% in big turnover, breaking out from a flat base with an