Stock index futures were flat on Wednesday after fours days of gains drove the S&P 500 to new highs, leaving the index near levels reached just before Lehman Brothers went bankrupt two years ago.

* Despite several technical indicators pointing to an overbought market after the S&P 500 climbed over 6 percent this month, interest from institutional investors could sustain a thinly traded market through the holiday period.

* There seems to be a pretty good rush to get more fully invested before the year is up, said Rick Meckler, president of investment firm LibertyView Capital Management in New York. The hedge funds and mutual funds who have been underweighted have used the last several days to bring themselves back to neutral if not a long position.

* High levels of bullishness and the S&P 500 relative strength index (RSI) are among indicators pointing to an overbought condition, but Meckler said that was unlikely to be worked off before traders return in force in January.

* The investment focus has shifted from fears of deficit spending to a lot excitement over the liquidity that's been added to the market, said Meckler. We are in an overbought condition, but there wont be enough people around from now until the end of the year to bring it off.

* S&P 500 futures rose 0.3 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 futures rose 4 points, while Nasdaq 100 futures fell 1.5 points.

* Resource-related stocks will be in focus as crude oil futures rose to 0.4 percent to top $90 a barrel after data showed a drop in U.S. oil and gasoline inventories amid a winter cold snap in the United States and Europe.

* In a relatively quiet week for economic data, the existing home sales report is due at 10:00 a.m. EST (1500 GMT), while the final estimate of third-quarter gross domestic product is expected at 8:30 a.m. EST (1330 GMT). The data will likely need to be outliers to drive the market in either direction.

* Existing home sales are seen rising to 4.71 million in November, compared with 4.43 million in the prior month, while Q3 final GDP is seen up 2.8 percent versus the prior reading of 2.5 percent, according to a Reuters survey.

* Shares of Boeing Co may be in the spotlight after the company said it was set to announce the resumption of test flights for its 787 Dreamliner plane, which have been halted since last month due to technical problems.

* Also in view, Microsoft Corp is working on a version of its core Windows operating system for devices such as tablets, according to reports. Also, the company said its Windows Phone 7 software is making headway in the booming smartphone market.

* Investors will keep an eye on geopolitical hot spots. South Korea announced military exercises, including its largest-ever live-fire drill near North Korea just as tensions on the peninsula were beginning to ease after Pyongyang's attack on a southern island.

* European shares were flat on Wednesday, while Japan's Nikkei average <.N225> dipped 0.2 percent, backing away from a seven-month intraday high reached earlier after downbeat comments from the prime minister on the economy.

(Reporting by Edward Krudy; editing by Jeffrey Benkoe)