The autumn pullback in the stock market worsened Friday, pushing the S&P 500 into a correction and to its worst two-week decline of the year.  

The broad stock-market gauge wavered for much of the day before turning lower and losing 0.5% for the session, bringing it down more than 10% from its recent high. A drop in shares of Chevron and JPMorgan Chase helped send the Dow Jones Industrial Average down 367 points, or 1.1%, to its lowest closing level since March.