Stocks fell heavily in the first two days of trading this week on concerns about the health of China's economy. The market then rebounded over the next two days as investors decided the sell-off was overdone.
The Dow Jones industrial average fell 52 points, or 0.3 percent, to 16,595 as of 12:07 p.m. Eastern time Friday.
The Standard & Poor's 500 index slipped six points to 1,981. The Nasdaq composite rose dropped 11 points, or 0.2 percent, to 4,800.
U.S. oil prices moved sharply higher for a second day.
Bond prices were little changed. The yield on the 10-year benchmark Treasury note edged down to 2.17 percent from 2.18 percent.