NEW YORK (Reuters) - Energy stocks climbed on Tuesday as oil prices surged above $81 a barrel, but U.S. shares ended lower as chipmakes fell on ratings downgrades and rate-sensitive shares lost ground ahead of an expected Federal Reserve interest rate hike.

Traders work on the floor of the New York Stock Exchange (NYSE) in New York, U.S., September 21, 2018. REUTERS/Brendan McDermid

The dollar weakened as the expected Fed rate hike has already been priced in by investors.

The Dow Jones Industrial Average .DJI fell 69.84 points, or 0.26 percent, to 26,492.21, the S&P 500 .SPX lost 3.81 points, or 0.13 percent, to 2,915.56 and the Nasdaq Composite .IXIC added 14.22 points, or 0.18 percent, to 8,007.47.

The pan-European FTSEurofirst 300 index .FTEU3 rose 0.54 percent and MSCI's gauge of stocks across the globe .MIWD00000PUS gained 0.04 percent.

“A lot of the noise around trade and anything else around politics really hasn’t suppressed consumer confidence nearly to the degree that the other factors have boosted it,” said Mike Dowdall, investment strategist for BMO Global Asset Management, in Chicago.

Brent crude futures LCOc1 touched a four-year high, at $82.55 a barrel, catapulted by imminent U.S. sanctions on Iranian crude exports and the apparent reluctance of OPEC and Russia to raise output to offset the potential hit to global supply.[O/R]

Oil prices pared gains, however, after U.S. President Donald Trump, in a speech before the United Nations, called on OPEC again to boost crude output.

“The combination of tight supply, healthy demand, falling global inventories – down from already under-stored levels – and anemic spare capacity helps support an oil price which could end the year above $90,” Richard Robinson, manager of Ashburton’s Global Energy Fund, said.

U.S. crude CLcv1 fell 0.01 percent to $72.07 per barrel. Brent LCOcv1 was last at $81.56, up 0.44 percent on the day.

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The rise in energy shares, however, failed to squash broader market pessimism a day after Washington and Beijing imposed new tariffs on each other’s goods, and Chinese Vice Commerce Minister Wang Shouwen accused the United States of putting “a knife to China’s neck.”

There are other big worries for investors too, not least the timing and pace of central bank policy tightening.

The Fed is widely expected to hike rates when it ends its two-day policy meeting on Wednesday, in a third increase in 2018. European Central Bank President Mario Draghi on Monday raised expectations the euro zone will also start to normalize policy over the coming year by referring to “relatively vigorous” underlying inflation and brisk wage growth.

U.S. 10-year Treasury yields held near a new four-month high above 3.10 percent after a $38 billion government debt sale on Tuesday. [nL2N1WB1C1]

Benchmark 10-year notes US10YT=RR last fell 6/32 in price to yield 3.0983 percent, from 3.078 percent late on Monday.

The U.S. dollar weakened ahead of the Fed’s policy decision, as investors have already priced in two more interest rate increases this year and some in 2019, leaving little room for further currency gains.

The dollar index .DXY fell 0.05 percent, with the euro EUR= up 0.18 percent to $1.1767.

Since mid-August, the dollar has declined 3.1 percent against the index’s basket of six major currencies.

“The U.S. dollar appears vulnerable ... given extended speculative bullish positioning against most of the G10 currencies and considerable tightening already reflected in fed funds futures,” said Eric Theoret, currency strategist at Scotiabank in Toronto.

The drifting dollar helped gold edge higher. Spot gold XAU= added 0.2 percent to $1,200.71 an ounce.