Stock index futures fell on Wednesday, pointing to a sixth day of losses in an enduring downtrend as investors worry about the bleak economic outlook and technical market indicators point to more weakness ahead.

Stocks reversed tentative gains late in the last session after Federal Reserve Chairman Ben Bernanke acknowledged the economy has slowed but offered no hint the U.S. central bank is considering any more stimulus to accelerate growth.

Oliver Pursche, president of Gary Goldberg Financial Services in Suffern, New York, said the market was likely hoping for some hint of action from the Fed after its second round of bond buying expires at the end of the month. He said the market will sell off past the end of the second phase of quantitative easing, known as QE2, into July.

The catalyst for a reversal of this is going to be a realization by the market that the end of asset purchases as defined by QE2 is a far, far cry from the end of easy monetary policy, he said. We are being opportunistic and adding to positions we really like as they sell off.

The S&P 500 has taken out successive lows in the recent downdraft, falling almost 6 percent since a peak in early May, with some technical analysts looking for a pullback to the March lows in the index at around 1,250, around 3 percent below its close on Tuesday. A fall of 10 percent would be considered a correction.

S&P 500 futures fell 6.3 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 59 points, and Nasdaq 100 futures fell 16.75 points.

The S&P 500 is now up just over 2 percent for the year so far. Pursche said he would not be entirely surprised to see the index return to support at 1,250.

OPEC oil producers were split on whether to back a Saudi-led plan to increase supply and try to cap inflated world crude prices as they meet in Vienna. A decision to increase production could hit crude prices.

U.S. light crude fell by more than $1 as investors awaited the outcome of the OPEC meeting to see whether production quotas would be increased.

European shares <.FTEU3> fell 1.2 percent on Wednesday on weaker mining companies, while the Nikkei average <.N225> finished slightly higher, holding above key support near the bottom of its post-earthquake range as foreign investors were lured by cheap valuations.

U.S. drugmaker Merck & Co will discontinue a major trial of a key vaccine from Intercell designed to protect against serious hospital infections, the Austrian biotech firm said on Wednesday.

The Fed issues its Beige Book, a summary of economic conditions in the 12 Federal Reserve districts, at 2 p.m. EDT.

Covidien Plc is looking to sell its pharmaceuticals unit for as much as $4 billion, a source familiar with the situation said on Tuesday.

(Editing by Padraic Cassidy)