Major U.S. stock indexes rallied Friday to finish one of their most tumultuous weeks in memory on a high note, buoyed by strong earnings from Apple and other big companies.

The move—capped off with a late-afternoon rally—was good news for investors after a nerve-racking January set to wrap-up Monday. The S&P 500 and Dow Jones Industrial Average snapped three-week losing streaks and the Nasdaq rose more than 3% on the day to finish a wild week flat.