U.S. stocks fell in early trading on Wednesday as investors waited for the release of minutes from last month's Federal Reserve meeting for clues on when interest rates would be increased. Most U.S. Treasuries prices were higher, with yields hitting a session high, as concerns about Greece's ability to meet its debt payments renewed safe-haven demand for bonds ahead of the release of details of the Fed's meeting. The minutes of meeting are due at 2:00 p.m. ET (1800 GMT). The central bank has said it will raise rates only when data suggests that the economy is strengthening. Growth slowed to a crawl in the first quarter. Recent data has painted a mixed picture. Consumption, business spending and manufacturing data has suggested the economy is struggling, but housing starts were strong.

While the Fed is broadly expected to raise rates this year, the timing of the move has kept the market on tenterhooks. "There is a consensus that the Fed probably doesn't move until September and I don't think that will change today," said Art Hogan, chief market strategist at Wunderlich Securities in New York. The latest Reuters survey showed most economists were now less convinced about when rates would be increased, but the median still suggested a move in the third quarter. A rate hike is not likely to be appropriate until early 2016, Chicago Fed President Charles Evans said on Wednesday. At 9:43 a.m. ET (1343 GMT) the Dow Jones industrial average was down 25.05 points, or 0.14 percent, at 18,287.34, the S&P 500 was down 4.59 points, or 0.22 percent, at 2,123.24 and the Nasdaq Composite was down 16.26 points, or 0.32 percent, at 5,053.78. Eight of the 10 major S&P 500 indexes were lower.

The industrials index fell 0.44 percent as Southwest Airlines led a drop in airline stocks. Southwest fell 6 percent to $38.33 after it forecast a decline in passenger revenue per available seat mile for the quarter. Yahoo Inc gained 3.7 percent to $42.60 after the company said a potential change in tax rules on spinoffs was not specific to its plan to spin off its stake in Alibaba. The stock fell 7.6 percent on Tuesday.