By Victor Reklaitis, MarketWatch

Twitter dives in premarket action, while Gilead jumps

U.S. stock futures pared modest gains early Wednesday, as investors assumed a cautious posture ahead of the Federal Reserve statement due to be released in the afternoon.

S&P 500 futures were flat at 2,087.25, while those for the Dow Jones Industrial Average up about 18 points, or 0.1%, to 17,564.00. Nasdaq-100 futures added 2.25 points, or 0.1%, to 4,558.25.

On Tuesday, the U.S. stock market climbed and halted a five-session losing streak (http://www.marketwatch.com/story/us-stock-futures-climb-with-key-fed-meeting-in-focus-2015-07-28), as the Dow gained nearly 190 points and fears about a recent Chinese stock selloff abated somewhat. The S&P 500 jumped 1.2% for its biggest rise in more than two months.

Fed announcement: The U.S. central bank is wrapping up a two-day meeting and will release a brief statement at 2 p.m. Eastern Time. No news conference has been scheduled.

While the Fed is unlikely to tip its hand about whether it will raise interest rates at its September meeting, investors nonetheless will read its latest policy statement closely.

"A July rate hike looks unlikely, but a September liftoff appears to be well on the way to being priced into currency markets, so any hints that come out of the statement could have a significant impact on trading," said Colin Cieszynski, chief market strategist at CMC Markets, in a note late Tuesday.

See: Fed seen staying mum (http://www.marketwatch.com/story/fed-seen-staying-mum-but-second-quarter-gdp-report-pencils-out-as-game-changer-2015-07-26)

In other U.S. economic news, a June reading for pending home sales is expected at 10 a.m. Eastern.

Other markets: Chinese stocks mostly closed higher Wednesday, with the Shanghai Composite up 3.4% and recovering partly from Monday's 8.5% slide (http://www.marketwatch.com/story/china-stocks-remain-weak-as-investors-focus-on-the-fed-2015-07-29) that helped spark a global selloff. But the gains baffled many analysts, who suspected Chinese government buying. European equities on Wednesday mostly gained ground (http://www.marketwatch.com/story/european-stocks-step-up-as-investors-wait-for-fed-2015-07-29).

Crude-oil prices dropped, while gold and the dollar (http://www.marketwatch.com/story/dollar-holds-steady-against-yen-euro-ahead-of-fomc-2015-07-29) were little changed.

Movers & Shakers: Citrix Systems Inc. (CTXS) was the biggest gainer among S&P 500 stocks in premarket action, jumping 4.6% after the software company's adjusted quarterly profit and revenue topped expectations late Tuesday (http://www.marketwatch.com/story/citrix-systems-ceo-mark-templeton-to-retire-2015-07-28-174854715). Citrix also announced the retirement of its long time chief executive, Mark Templeton.

Gilead Sciences Inc. (GILD) was the second-biggest S&P winner in premarket trade, rising 3.5% after the biotech company late Tuesday posted adjusted quarterly profit and revenue that beat forecasts (http://www.marketwatch.com/story/gilead-rallies-after-earnings-beat-wall-streets-expectations-2015-07-28).

Altria Group Inc. (MO) advanced after posting better-than-expected quarterly results (http://www.marketwatch.com/story/altrias-stock-rallies-after-profit-sales-rise-above-expectations-2015-07-29) before the open, while Humana Inc. (HUM) reported quarterly profit and revenue that missed Wall Street's forecasts (http://www.marketwatch.com/story/humana-misses-profit-sales-expectations-2015-07-29).

Twitter Inc. (TWTR) was down 11% premarket after its earnings report late Tuesday, with investors focusing on the social-media company's disappointing user growth (http://www.marketwatch.com/story/twitter-revenue-jumps-user-growth-disappoints-2015-07-28). Yelp Inc. (YELP) shares dived 23% after a quarterly report (http://www.marketwatch.com/story/yelp-chops-forecast-chairman-to-step-down-2015-07-28) that dismayed investors.

After the closing bell, Whole Foods Market Inc. (WFM) and Facebook Inc. (FB) results are due.

Read more: MasterCard, Facebook, Humana earnings in focus (http://www.marketwatch.com/story/mastercard-facebook-humana-earnings-in-focus-2015-07-28)

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