New York ? Stocks dropped in light summer trading Friday after Apple Computer Inc. said its mishandling of employee stock options would require it to make significant changes in its third-quarter results compared to last year’s earnings.

Investors also had broader worries, especially fears of an economic slowdown. A steep increase in retail sales did little to allay those worries.

“We’re in a seasonally slow part of the year and there are a lot of unknowns on the horizon right now,” said Mike Malone, trading analyst, Cowen & Co. “Based on that, there really is no urgency to get overly aggressive.”

Every sector fell despite cheery retail sales numbers reported by the Commerce Department. Retail sales rebounded in July by 1.4 percent, the biggest gain in six months. June’s revised sales numbers were down 0.4 percent, much weaker than the 0.1 percent dip originally reported.

Any optimism investors feel appears fragile. Investors had been waiting for the Federal Reserve to pause its streak of interest rate hikes and when it did, on Tuesday, stocks fell anyway.

“There’s a sense that the market’s never happy,” said Ryan Larson, a senior equity trader at Voyageur Asset Management Inc. in Chicago. “They want one thing and when they get it, the next day we’re on to something else.”