* Fed statement expected at 2 p.m. ET
* Twitter slumps after monthly average users growth slows
* General dynamics leads aerospace stocks higher
* Indexes up: Dow 0.59 pct, S&P 0.49 pct, Nasdaq 0.18 pct (Updates to early afternoon)
By Tanya Agrawal
July 29 (Reuters) - U.S. stocks rose on Wednesday as investors assessed earning ahead of a statement from the U.S. Federal Reserve that could give clues regarding the timing of a rate hike.
Investors are focused on the outcome of the Fed's two-day policy meeting with markets divided on whether it will take a hawkish or dovish stance. No move on rates is expected this week.
In a recent congressional testimony, Fed Chair Janet Yellen neither ruled out a September interest rate hike nor guided the market toward thinking it was a done deal. The statement is expected at 2 p.m. ET (1800 GMT).
U.S. interest rates have remained near zero for almost a decade and the Fed has said it will raise rates once it sees a sustained recovery in the economy.
Recent concerns surrounding the Greek debt crisis and the rout in Chinese markets have prompted some investors to bet that the Fed may hold off raising rates until the end of the year.
"I don't expect anything different out of the FOMC meeting today. Investors tend to take a cautious stand ahead of such meetings and that's why we aren't seeing too much a rally today," said Art Hogan, chief market strategist at Wunderlich Securities in New York.
At 12:50 a.m. ET, the Dow Jones industrial average was up 104.29 points, or 0.59 percent, at 17,734.56, the S&P 500 was up 10.24 points, or 0.49 percent, at 2,103.49 and the Nasdaq Composite was up 9.37 points, or 0.18 percent, at 5,098.58.
Nine of the 10 major S&P sectors were higher with the telecommunications index's 1 percent rise leading the advancers.
Pledges from Chinese regulators to buy shares to stabilize stocks if needed and hints of more policy easing from the central bank also soothed sentiments.
U.S. stocks ended sharply higher on Tuesday, breaking a five-day losing streak as attention shifted from trouble in Chinese equities to U.S. corporate earnings.
With second-quarter reports well under way, analysts now expect overall earnings of S&P 500 companies to edge up 0.8 percent and revenue to decline 3.9 percent, according to Thomson Reuters data.
While earnings are expected to increase this quarter, valuations remain a concern. The S&P 500 is trading near 16.9 times forward 12-month earnings, above the 10-year median of 14.7 times, according to StarMine data.
"Earnings have been fairly good but the problem is that we haven't seen organic revenue growth and are also seeing tepid guidance from companies in face of the strong dollar," said Hogan.
Companies scheduled to report after the bell include Facebook MetLife and Whole Foods Market.
Twitter shares fell as much as 14.3 percent to a year-low of $31.30 after the microblogging company said its number of monthly average users rose at the slowest pace since it went public in 2013.
Yelp slumped as much 29.4 percent to a nearly two-year low of $23.66 after the operator of consumer review website Yelp.com, reported a surprise loss and forecast disappointing revenue for the current quarter.
Cytec soared 26.5 percent to $15.45 after Belgian chemical group Solvay agreed to buy the company for $5.5 billion.
General Dynamics rose as much as 6.3 percent to hit a record high of $153.39 after earnings, and lead a sector-wide rally across major aerospace stocks. Northrop Grumman, Spirit Aerosystems, Lockheed Martin and Transdigm Group were all up between 2.5 percent and 7.4 percent.
Advancing issues outnumbered decliners on the NYSE by 2,087 to 882. On the Nasdaq, 1,536 issues rose and 1,120 fell.
The S&P 500 index showed 25 new 52-week highs and one new lows, while the Nasdaq recorded 41 new highs and 56 new lows. (Editing by Don Sebastian)