Was that a case of quarter-end buying by institutions? Over the last 50 minutes of the trading session on Wednesday, the S&P 500 (SPX) took off like a rocket, surging 30 points and finishing 0.9% higher on the day and at another all-time high. But the biggest winners on the day were small-caps, with the Russell 2000 (IWM) surging 2.2% and the S&P 600 (SML)