By Sara Sjolin and Carla Mozee, MarketWatch

Mexican peso rallies after Clinton and Trump face off

U.S. stock futures gave up post-debate gains and turned lower Tuesday as worries over troubled Deutsche Bank put pressure on global equities while sliding oil dented sentiment.

Crude-oil prices dropped nearly 3% after both Iran and Saudi Arabia played down expectations for a deal to freeze or cut oil production at the closely watched informal OPEC meeting on Wednesday.

Futures had rallied overnight after the closely watched U.S. presidential debate between Democratic candidate Hillary Clinton and Republican contender Donald Trump late Monday.

The early boost in futures may be interpreted by as supportive for U.S. equity markets because Trump is perceived by some as being more unpredictable.

"It's clear that U.S. stock futures got a boost after Clinton's superior performance at the debate but as soon as European markets opened Deutsche Bank worries came back. Germany's DAX index is down more than 1% and negative sentiment is spilling over," said Mark Kepner, managing director of sales and trading at Themis Trading.

"A sharp turn in oil prices is also putting pressure on stocks," added Kepner.

Futures for the Dow Jones Industrial Average were off 30 points, or 0.2%, to 17,986 after being up by triple digits earlier in the premarket session. Futures for the S&P 500 index was off 3.45 points, or 0.1%, to 2,136. Futures for the Nasdaq-100 index retreated 2.75 points, or 0.1%, to 4,812.00.

Read:At debate, Trump and Clinton clash on how to remake the economy (http://www.marketwatch.com/story/how-trump-and-clinton-want-to-remake-the-economy-2016-09-26)

However, the main focus early for investors was Monday night's presidential debate and how it could influence the direction of the economy and the global market.

"The perception on Wall Street is that [Clinton] would be the safer pair of hands, but with two further debates and six more weeks of campaigning to go, this race seems set to be a bountiful source of market volatility in the near term," Paul Webb, deputy CEO at ADS Securities London, in a note.

Oil prices on Tuesday dropped sharply after Iran and Saudi Arabia poured cold water on hopes (http://www.marketwatch.com/story/oil-prices-lower-after-iran-douses-hopes-for-production-deal-2016-09-27) for a production-cap deal at the oil producers' meeting this week. The Wednesday meeting, on the sidelines of an energy conference in Algeria, will be "consultative," both nations said.

Also weighing on oil prices, Goldman Sachs cut its fourth quarter forecast for crude oil to $43 a barrel from $50 expected previously (http://www.marketwatch.com/story/goldman-cuts-q4-wti-oil-forecast-to-43-a-barrel-from-50-2016-09-27).

On Monday, U.S. stocks ended lower (http://www.marketwatch.com/story/us-stocks-brace-for-sharp-losses-in-nervous-wait-for-presidential-debate-2016-09-26), as concerns about the outcome of the debate weighed on sentiment. After the debate, Accendo Markets noted that it is "still early days" to dismiss Trump's chances.

"Trump could be setting the bar low for the remaining faceoffs. And he does have a 'bouncebackability' that has already helped his campaign get within touching distance of the Oval Office," Accendo said in a note.

Mexico wave: In another sign suggesting financial markets (http://www.marketwatch.com/story/financial-markets-say-clinton-beat-trump-in-the-debate-2016-09-26) pegged Clinton as the debate winner, the Mexican peso surged against the dollar on Tuesday. The greenback fell to 19.535 pesos, down from 19.879 pesos late Monday in New York.

The peso has been acting as a gauge of the presidential election sentiment on the theory that a victory for Trump will at the very least result in less trade between the two countries, if not the building of a barrier on the U.S. southern border.

The U.S. Dollar Index , a measure of the buck's strength against a basket of six key rivals, was up 0.1% at 95.419.

Economic docket: At 9 a.m. Eastern Time, the Case-Shiller home price index for July is released, followed by the Markit flash services purchasing managers index for September at 9:45 a.m. Eastern.

Then at 10 a.m. Eastern, the consumer confidence reading for September is due, expected to slip back to 99.3 from 101.1 in August, according to economists polled by MarketWatch.

Federal Reserve Vice Chairman Stanley Fischer will give a speech on 'Why Study Economics' at Howard University's Economic Convocation in Washington DC at 11:15 a.m. Eastern.

Stocks to watch: U.S.-listed shares of Deutsche Bank AG(DBK.XE) dropped 2.9% in premarket trade, extending losses from Monday when a report said German Chancellor Angela Merkel has rules aid state aid for the lender.

Read:How Deutsche Bank woes are stressing out the U.S. stock market (http://www.marketwatch.com/story/how-deutsche-bank-woes-are-stressing-out-the-us-stock-market-2016-09-26)

(http://www.marketwatch.com/story/how-deutsche-bank-woes-are-stressing-out-the-us-stock-market-2016-09-26)Shares of EndoChoice Holdings Inc.(GI) soared 87% in premarket trade after Boston Scientific Corp. (BSX) said it would buy the medical technology company for roughly $210 million (http://www.marketwatch.com/story/boston-sci-to-buy-endochoice-for-210-million-2016-09-27).

(http://www.marketwatch.com/story/how-deutsche-bank-woes-are-stressing-out-the-us-stock-market-2016-09-26)FactSet Inc.(FDS) slipped 0.7% ahead of the bell, even after posting a rise in earnings and revenue (http://www.marketwatch.com/story/factset-profit-and-revenue-rise-2016-09-27) in its fiscal fourth quarter.

Kite Pharma Inc.(KITE) surged 12% before the open after the drugmaker late Monday released encouraging test results for its for its non-Hodgkin lymphoma drug.

Nike Inc.(NKE) will report earnings after the market's close (http://www.marketwatch.com/story/what-to-watch-for-in-nike-earnings-2016-09-23).

Other markets: Stocks in Europe were falling (http://www.marketwatch.com/story/european-stocks-slide-as-us-debate-cheer-fades-2016-09-27) after rising at the open as oil's slide dragged on the energy sector. In Asia, shares reversed earlier declines as investors reacted to the U.S. presidential debate (http://www.marketwatch.com/story/asian-shares-turn-mostly-higher-in-wake-of-us-presidential-debate-2016-09-27), with the Nikkei Stock Average closing up 0.8%.

Gold futures fell 0.3% to $1,336.10 an ounce.

(END) Dow Jones Newswires

September 27, 2016 09:15 ET (13:15 GMT)

Copyright (c) 2016 Dow Jones & Company, Inc.