Wall Street was set to open little changed on Wednesday as investors cautiously awaited the outcome from the Federal Reserve's policy-setting meeting that is likely to include new measures to boost the economy.

The Fed, ending a two-day policy meeting later Wednesday, is expected to announce a rebalancing of its bond portfolio weighted more heavily to longer-term securities, pushing already-low long-term interest rates even lower in a move dubbed Operation Twist.

The Fed will issue a statement at about 2:15 p.m.

The market is anticipating Operation Twist, which will help, but certainly not jump-start the economy, said Scott Brown, chief economist at Raymond James in St. Petersburg, Florida.

We might see some disappointment and a selloff in the market if that is the only measure from the Fed.

S&P 500 futures were off 0.2 point but in line with 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 lost 28 points, and Nasdaq 100 futures rose 1.75 points.

The National Association of Realtors is due to report existing home sales data for August at 10 a.m. EDT. (1400 GMT) Economists polled by Reuters predicted a 1.4 percent increase for August, following a 3.5 percent decline in July.

Oracle Corp forecast higher-than-expected current-quarter earnings and robust software sales, reassuring investors that global technology spending was holding up. Oracle shares rose 3.6 percent to $29.38 in premarket trade.

Design software maker Adobe Systems Inc's sales outlook for the fourth quarter was buoyed by new customer additions. The stock jumped 5.5 percent to $26.00 premarket.

General Motors Co's chief executive told Reuters he is concerned about the risk of another U.S. recession, but he said pent-up demand was likely because of the need to replace aging cars in the world's biggest economy.

European shares were down 0.8 percent on Wednesday after strong gains the previous day, although technology shares outperformed after Oracle's upbeat outlook. <.EU>

U.S. stocks ended little changed on Tuesday in the lowest volume session since late August as investors waited to see if the Fed would offer more economic stimulus and if Greece made progress in talks to avoid a default.

(Reporting by Angela Moon; editing by Jeffrey Benkoe)