Stocks have been zigzagging on no major data, but then it's quadruple witching day, raising expectations for a good close to match the positive open. At midday, the Dow +0.5% to 9834; S&P 500 +0.3% to 1069; Nasdaq +0.3% to 2134. Crude -0.5%. Natural gas +5.6%. Gold -0.3%.