U.S. stock index futures pointed to a flat open on Wednesday, as investors found few reasons to keep buying after a rally that has taken indexes to repeated records, even as there was little seen on the horizon that could derail the rally.

On Tuesday, the S&P 500 .SPX closed above 2,000 for the first time while the Dow .DJIended near a record high. Both indexes have risen in 10 of the past 13 sessions, and the S&P has closed at a record 30 times this year, according to S&P Dow Jones Indices.

The S&P's price-to-earnings ratio is within historical norms, suggesting stocks are not overvalued, even at record levels. Nonetheless, further pronounced gains may be a challenge, given the few positive catalysts as well as potential headwinds like a reduction in U.S. Federal Reserve stimulus and the conflict between Ukraine and Russia.

Markets haven't undergone a correction since 2012, giving analysts another reason to expect a pullback. Much of the recent gains have come on low volume, suggesting investors are reluctant to jump in at current levels.

S&P 500 e-mini futures ESc1 rose 0.25 point and were above fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average e-mini futures 1YMc1 rose 10 points and Nasdaq 100 e-mini futures NQc1 added 0.5 point.

In company news, Tiffany & Co (TIF.N) rose 1.2 percent to $102 in premarket trading after reporting second-quarter revenue that topped expectations and raising its full-year profit view.

Chico's FAS Inc (CHS.N) fell 5.4 percent to $15.16 before the bell after its results.

Chipmaker Qualcomm Inc (QCOM.O) may face a European investigation related to a four-year-old complaint from a subsidiary of rival Nvidia Corp (NVDA.O), sources told Reuters.

Allergan Inc (AGN.N) said late Tuesday it scheduled a special shareholders meeting for Dec. 18. Activist investor Bill Ackman, who supports a hostile bid for the company by Valeant Pharmaceuticals Inc (VRX.TO), will attempt to oust most of the Allergan board.

Digital Ally Inc (DGLY.O) rose 1.5 percent to $14.49 in premarket trading, extending a massive rally that has lifted shares more than 270 percent in August alone. The wearable camera maker has reported heightened demand since Aug. 9, when a white police officer shot and killed an unarmed black teen in Ferguson, Missouri, triggering weeks of protests.

The situation between Russia and Ukraine has faded as a market driver. In comments that could escalate the standoff, however, Ukrainian Prime Minister Arseny Yatseniuk said Kiev knew of plans by Russia to halt gas flows this winter to Europe.

(Editing by Jeffrey Benkoe and James Dalgleish)