NEW YORK — Investors seem to be running short on hope.

With little upbeat news ahead of a crush of corporate earnings reports next week, stocks on Friday hit their longest losing streak since the market's spring rally began in early March.

Unrelenting worries over the economy, driven by poor reports on unemployment, consumer confidence and falling commodity prices, have kept investors largely out of stocks since mid-June.

"Nobody's investing because there's no reason to invest," said Dawn Bennett, CEO of Bennett Financial Group.

Stocks zigzagged during the week, failing to hold what few gains they could muster. The Dow Jones industrials and the Standard & Poor's 500 index have now fallen four straight weeks.

Investors are on edge as the second-quarter earnings season heats up. Aluminum maker Alcoa Inc. unofficially kicked off the period with better-than-expected results on Wednesday, but a warning from Chevron Corp. late Thursday put investors back on the defensive. Alcoa and Chevron are among the 30 stocks that make up the Dow.

The pace of reports picks up speed next week with results coming in from heavy hitters such as Johnson & Johnson, JPMorgan Chase & Co., Google Inc. and General Electric Co.

Investors are looking to the reports, and especially the forecast companies give on the remainder of the year, for insight into where the economy is headed. Expectations are generally low.

According to preliminary calculations, the Dow Jones industrial average fell 36.65, or 0.5 percent, to 8,146.52. The Standard & Poor's 500 index lost 3.55, or 0.4 percent, to 879.13, while the Nasdaq composite index rose 3.48, or 0.2 percent, to 1,756.03. A handful of upgrades to technology shares helped shore up the Nasdaq.

For the week, the Dow lost 1.6 percent, the S&P 500 index slide 1.9 percent and the Nasdaq lost 2.3 percent.