Global stock markets have suffered more turbulence as investors reacted to mixed signals on global trade tensions.
The S&P 500 erased an early-morning rise to drop to its lowest closing level in nearly a month.
One of the day's few market certainties was oil's continued rise, and benchmark US crude hit its highest price since 2014.
That helped lift energy stocks but other areas of the market went up and down as the day progressed.
Early on, Asian stocks slumped on concerns about the sometimes heated talk on trade that has been ongoing between the United States and its partners.
European stocks later flipped from losses to gains on hopes that a move by the Trump administration indicated a less combative stance with China.
US stocks opened higher, but the gains evaporated after a White House adviser said the move was not necessarily a signal of a softer stance.
By the end of the day, the S&P 500 fell 23.43 points, or 0.9%, to 2,699.63 after earlier being up as much as 0.8%.
The Dow Jones industrial average lost 165.52, or 0.7%, to 24,117.59, the Nasdaq composite gave up 116.54, or 1.5%, to 7,445.08 and the Russell 2000 index of small-cap stocks fell 28.07, or 1.7%, to 1,640.45.
Stocks have swung in recent weeks, even by the hour, on worries about global trade.
Investors were feeling less nervous about it in the morning after the Trump administration indicated it's shifting away from a plan to impose limits on Chinese investment in US technology companies and high-tech exports to China.
Instead, the administration is calling on Congress to enhance an existing review process.
Markets took it as a sign of a less antagonistic stance, but the gains disappeared in the afternoon after Larry Kudlow, director of the National Economic Council, said in an interview with Fox Business that it should not necessarily be viewed as a softer stance.
"Trade is the hot topic du jour, and it's having an impact on the market" said Barry Bannister, head of institutional equity strategy at Stifel.
It's only adding to pressures that have been mounting on the market.
The Federal Reserve is raising interest rates, but more importantly to Mr Bannister, interest rates after accounting for the effects of inflation are set to cross key thresholds.
That is putting pressure on stock prices, and he says this bull market that began in 2009 may end by the first quarter of 2020.