US Markets

Wall Street under pressure as Fed minutes take center stage

U.S. stock index futures indicated a lower open on Wednesday, with investors on edge before the release of the U.S. Federal Reserve's minutes from its July meeting, marking one of the last big days before its September rate-setting meeting.

The minutes of the Fed's July meeting are expected to be released at 2 p.m. ET, and traders are hoping the Fed minutes will give new insight into Fed thinking on rate hikes that did not come out in the post-meeting statement.

Read MoreOne of the final big Fed days before mid-September

Traders work on the floor of the New York Stock Exchange.
Brendan McDermid | Reuters

The timing of the U.S. central bank's first rate hike in nine years has been a constant source of debate in the markets, as traders await the final pieces of economic data the Fed will take to its September rate meeting. Minutes of the Fed's July meeting, to be released Wednesday afternoon, could give investors some clarity.

Before that, the consumer price index will be released at 8:30 a.m. and will be important if it brings any surprises, especially a lower-than-expected pace of inflation.

There are just a few more big pieces of data the market is watching before the Fed meets on September 16 and 17. The Fed has indicated that it is data-dependent, so figures that cover its dual mandates of employment and inflation count the most. So first and foremost, markets are awaiting the employment report on September 4, then PPI on Sept. 11 and CPI on Sept. 16.

Read MoreSt. Louis Fed official: No evidence QE boosted economy

"Most likely, the minutes will be seen to support the view of the consensus amongst the commentators, but will fail to allay the fear of inaction amongst the traders/investors. And that would most likely leave markets still wracked by uncertainty, about the Fed, global growth and China. Too much to worry about to believe that risk aversion will melt away," said global strategist at Societe Generale, Kit Juckes.

The market will also be on the lookout for any Fed speakers, particularly after recent comments from Atlanta Fed President Dennis Lockhart signaled a willingness for the Fed to move.

On the earnings front, Lowe's posted earnings results that missed expectations, while Hormel Foods beat earnings per share estimates by 1 cent.

Staples reported earnings per share that matched estimates on revenue that was essentially in line. Target beat expectations on both lines. L Brands, NetApp, Synopsys, Momo, Popeyes Louisiana Kitchen are all due to report after the bell.

Outside of the U.S., equity markets in China hurled themselves back above the flatline late Wednesday after the Shanghai bourse closed down 6.1 percent in its biggest daily decline since July 27 in the previous session.

China's Shanghai Composite index cut losses to close up 1.2 percent in the final hour of trading. Earlier in the day, the Shanghai bourse dived more than 5 percent to touch its lowest level since August 6 before clawing back losses.

In Europe, shares were sharply lower, with most major bourses down over 1 percent ahead of the Fed's end-July Federal Open Market Committee meeting minutes.