Stock index futures pointed to a flat open on Wednesday after a three-day run-up as commodity prices were little changed after driving the market in recent days.

Shares of health insurers are in focus ahead of U.S. President Barack Obama's speech to Congress on Wednesday evening in which he will provide specifics about his vision for overhauling the healthcare system.

Gold and oil prices were little changed after gains in the commodities helped boost equities in the previous session. Oil rose above $71 a barrel as OPEC ministers were set to meet and expected to leave official output unchanged. Gold firmed but was below $1,000 after breaking through the key level on Tuesday for the first time since February.

After three days to the upside, for the most part following the commodities markets and the hope of more M&A activity, futures are taking a bit of a pause, said Arthur Hogan, chief market analyst at Jefferies & Co in Boston.

One of the keys that we've taken over the last few days ... has been a real correlation with what's going on in the commodities market. So it's not surprising to see a flat commodities market and a flat futures market.

In an encouraging sign for the ailing housing sector, mortgage applications surged last week with demand rising to its highest level since late-May, the latest data showed. A recovery in housing is seen as key to a sustainable economic rebound.

S&P 500 futures were off 0.30 points and were below 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 futures gained 4 points, and Nasdaq 100 futures slipped 2.50 points.

On the data front, investors will look at chain store sales from two separate reports. For details, see . Also, the Federal Reserve issues the Beige Book, a summary of economic conditions in the 12 Fed districts at 2:00 p.m. (1800 GMT).

Shares of Microchip Technology Inc rose 1.7 percent to $27.54 in late electronic trading on Tuesday after the chipmaker provided its second-quarter financial outlook.

Stocks advanced on Tuesday on an uptick in merger and activity, while the weak dollar led to gains in commodities, lifting shares of oil and mining companies.

The S&P 500 has rallied 52 percent from its multiyear low in March, and analysts still gave an upbeat outlook for the benchmark.

(Reporting by Leah Schnurr; editing by Jeffrey Benkoe)