U.S. stock index futures were marginally lower on Tuesday as investors braced for the result of a highly contentious U.S. presidential election, with the odds largely favoring Democrat nominee Hillary Clinton.
* Clinton has a 90 percent chance of defeating Republican nominee Donald Trump and was on track to win 303 votes in the Electoral College to Trump's 235, clearing the 270 needed for victory, according to the final Reuters/Ipsos States of the Nation poll released on Monday.
* The iShares MSCI Mexico Capped ETF, known of late as the "Trump ETF", inched up 0.4 percent, after notching its best day in more than five years on Monday. The ETF is viewed as a barometer of Trump's chances of winning the election since his policies are considered negative for Mexico.
* Investor appetite for riskier assets appeared to be low as Wall Street is also coming off its best day in more than eight months on Monday after the FBI said it would not press criminal charges against Clinton over her use of a private email server.
* "We had a surge in the markets yesterday, so today is just a waiting day to see the outcome of the election," said Peter Cardillo, chief market economist at First Standard Financial in New York.
* "We are going to see a market that is not going to do too much of anything today, probably slipping about the plus and minus columns," Cardillo said.
* The CBOE Volatility index, dubbed Wall Street's "fear gauge", was up 3 percent after having seen its biggest one-day drop since late June on Monday.
* Clinton has been favored by investors as they view her offering greater clarity and stability to the markets than Trump, whose stance on foreign policy, immigration and trade is more uncertain. A Clinton win is also perceived to not hinder the chances of the Federal Reserve raising interest rates next month.
* Still, traders remain wary, noting Britain's shock vote in June to leave the European Union had wrongfooted bookmakers and most pollsters.
* Safe haven assets such as gold and the yen were trading slightly higher, indicating heightened caution.
* The dollar was flat against a basket of currencies, coming off a near four-week high on Monday. Crude oil prices were little changed.
* Among stocks vying for attention was Hertz which slumped 33.3 percent to $23.84 in premarket trading after the car rental company slashed its full-year profit forecast.
* Valeant was the top traded stock falling 8.5 percent to $17.50 after the drugmaker reported a smaller-than-expected quarterly adjusted profit and cut its full-year profit and revenue forecasts.
* Priceline rose 5.3 percent to $1559 in light trading after the travel website operator reported quarterly profit and revenue that beat analysts' estimates.
Futures snapshot at 6:38 a.m. ET:
* Dow e-minis were down 23 points, or 0.13 percent, with 26,532 contracts changing hands.
* S&P 500 e-minis were down 4 points, or 0.19 percent, with 144,924 contracts traded.
* Nasdaq 100 e-minis were down 9 points, or 0.19 percent, on volume of 19,469 contracts.