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 .DJI ended 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.