The Dow and S&P 500 finished slightly higher on Tuesday, stabilizing after a weak start to the new year, though investor nervousness stayed high.
After weak Chinese economic data drove stocks down sharply on Monday, the People's Bank of China on Tuesday injected $20 billion into the financial system in a bid to help its markets.
A 2.5-per cent drop in Apple Inc weighed on all three major indexes, while a fall in crude oil prices and a stronger dollar contributed to the year's shaky start.
Wal Mart Stores Inc shares, up 2.4 per cent at $62.92, helped to lift both the Dow and S&P 500, though Monday's big selloff and renewed worries about China have contributed to caution about the year ahead.
"We're working off of a pretty significant decline on the first day of trading in 2016," said Mark Luschini, chief investment strategist at Janney Montgomery Scott in Philadelphia.
But "there are a lot of divergences on a macroeconomic, monetary and geopolitical front, any of which could undermine one's base case for how the year should unfold," he said. "I think it's leaving investors puzzled, and that shows up in these kinds of moves where you're trading off of noise rather than signal."
The Dow Jones industrial average rose 9.72 points, or 0.06 per cent, to 17,158.66, the S&P 500 gained 4.05 points, or 0.2 per cent, to 2,016.71 and the Nasdaq Composite dropped 11.66 points, or 0.24 per cent, to 4,891.43.
Advancing issues outnumbered declining ones on the NYSE by 1,812 to 1,277, for a 1.42-to-1 ratio on the upside; on the Nasdaq, 1,473 issues rose and 1,342 fell for a 1.10-to-1 ratio favoring advancers.
Apple shares were down 2.5 per cent at $102.71 after the Nikkei newspaper reported that the iPhone maker was expected to cut production of its 6S and 6S Plus models.
Among the day's bright spots, automakers set a new US sales record for 2015 even as December sales fell short of expectations. Shares of fell 1.8 per cent to $13.72 while shares of General Motors slipped 2.6 per cent to $32.43.
Gilead Sciences Inc rose 1.3 per cent to $99.26, after its experimental hepatitis B drug was found safer than, yet as effective, as its approved treatment Viread.
Eli Lilly & Co shares rose 1.5 per cent to $84.11 after the drugmaker said its diabetes treatment grabbed market share in the fourth quarter.
First Solar Inc was up 8 per cent at $72.02 after Goldman Sachs upgraded the stock to "buy."
The S&P 500 posted five new 52-week highs and six new lows; the Nasdaq recorded 23 new highs and 72 new lows.