Stock index futures were little changed on Tuesday before data on inflation that could shed light on the Federal Reserve's next move in dealing with a deteriorating credit environment.

Shares of Wal-Mart Stores Inc. fell after the world's largest retailer reported earnings that missed analysts' estimates and reduced its forecast for full-year profit from continuing operations.

Wal-Mart stock fell 3 percent to $44.80 in electronic composite trading.

The Producer Price Index for July, set for release at 8:30 a.m. EDT from the Labor Department, may attract more attention than normal since the U.S. central bank has stepped in repeatedly to provide money to the banking system. Any signs of quickening inflation could tie the Fed's hand for cutting rates to stave off a crisis in the credit markets.

We're looking for inflation data which can help add to the interest-rate debate. If there is a sharp rise, which isn't expected, that would make it more difficult for (Fed Chairman Ben Bernanke) to cut rates, said Peter Dunay, investment strategist at Leeb Capital Management in New York.

S&P 500 futures were up 2.1 points, slightly above fair value, a mathematical formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract.

Dow Jones industrial average futures were up 7 points, and Nasdaq 100 futures were up 1.25 points.

PPI is forecast to show a 0.2 percent gain in both overall prices as well as prices that exclude food and energy, or core PPI, according to economists surveyed by Reuters.

Home Depot Inc. (HD.N: Quote, Profile, Research), the world's largest home improvement retailer, reported a lower quarterly profit on Tuesday as the softer U.S. housing market hurt sales, but the results topped Wall Street estimates.

Shares of Home Depot were up almost 1 percent in trading before the opening bell.

Stocks ended little changed on Monday as credit worries haunted the market despite more cash infusions from central banks into the global financial system.