Quadruple Witching

Quadruple witching,” which marks the simultaneous expiration of a number of different options contracts. Stocks usually push higher during such periods, which can also bring jumpy trading. The gains followed those in markets overseas and a round of buying on Thursday. Better-than-expected economic data is suggesting that the United States economy might be in better shape than some investors had feared.

Traders drew some optimism from European Union leaders who said at a financial summit in Brussels that economic stimulus measures are cushioning the worst effects of the downturn. They said the steps would allow a sustainable economic recovery and that no new stimulus is needed right now.Health care, technology and retail stocks led the market, while consumer staples and utilities lagged.

In midmorning trading, the Dow Jones industrial average was 50 points higher, while the broader Standard & Poor’s 500-stock index rose 0.84 percent. The technology heavy Nasdaq increased 1.55 percent. Earlier, markets in Europe and Asia rose on newfound optimism by investors that the American economy may recover from recession this year.