* Staples shares tumble, Lowe's rises after results
* Fed minutes due at 2:00 p.m. EDT (1800 GMT
* Futures off: Dow 34 pts, S&P 4 pts, Nasdaq 10 pts
NEW YORK, Aug 21 (Reuters) - U.S. stock index futures dipped in thin trading Wednesday amid investor caution ahead of the publication of the minutes of the latest Federal Reserve policy-setting meeting.
* The S&P 500 rose on Tuesday to cap a four-day losing streak, but remained under technical pressure as it closed below its 50-day moving average for a third straight session. The benchmark closed roughly five points below that level, now at 1,657.65, which is becoming technical resistance.
* Retailers led gains in the previous session and will continue to be in focus in early trading as results from companies including Lowe's and Target take center stage.
* Investors have been grappling over the past several weeks with uncertainty over when the Fed will begin to wind down its $85 billion a month stimulus program. Minutes from the Fed's July meeting, which may provide clues about policymakers' plans for so-called quantitative easing, will be released at 2:00 p.m. EDT (1800 GMT).
* S&P 500 futures fell 4 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 fell 34 points, and Nasdaq 100 futures lost 10 points.
* Shares of Toll Brothers rose 1.1 percent in premarket trading after the largest U.S. luxury homebuilder reported a jump in revenue, showing signs of a recovering U.S. housing market.
* Shares of home improvement chain Lowe's rose 4.6 percent in premarket trading after it reported a bigger-than-expected rise in profit and sales as the housing market's recovery encouraged people to spend more on their homes.
* Staples reported weaker-than-expected quarterly results on dismal sales in international markets and cut its outlook for the year. Shares dropped 9.4 percent in premarket trading.
* A flood of erroneous trades hit U.S. equity options markets on Tuesday as they opened for business when Goldman Sachs sent orders accidentally because of a technical error, in the latest trading problem to hit markets.