* Indexes down: Dow 47 pts, S&P 5.25 pts, Nasdaq 2.25 pts
By Tanya Agrawal
Feb 8 (Reuters) - U.S. stock index futures edged lower on Thursday as investors took stock of a heavy round of corporate results after the most volatile week of trading in more than two-and-a-half years.
By 6:50 a.m. ET (1150 GMT), Dow e-minis were down 47 points, or 0.19 percent. S&P 500 e-minis were down 5.25 points, or 0.2 percent, with 226,163 contracts traded.
Nasdaq 100 e-minis were down 2.25 points, or 0.03 percent, on volume of 59,558 contracts.
Wall Street ran out of steam on Wednesday after an early surge as investors continued to question the nature of a sharp fall at the start of the week, which saw the Dow Jones Industrial Average notch its biggest intraday fall on record.
The market's main gauge of volatility, the CBOE Volatility Index, fell to 28.50 on Thursday, still more than twice levels it held over the past few months. The index hit its highest level since August 2015 on Tuesday.
Investors are weighing whether the sharp swings are the start of a deeper correction or just a temporary bump in the nine-year bull market, spurred by concerns over rising interest rates and bond yields.
Dallas Fed President Robert Kaplan said on Thursday the central bank could hike rates three times this year and the recent market volatility in itself was not enough to change his base scenario.
Philadelphia Fed President Patrick Harker, Minneapolis Fed chief Neel Kashkari and Kansas City Fed President Esther George are expected to make appearances at different events later in the day.
The 10-year U.S. Treasury yield crept back to 2.83 percent, near Monday's four-year peak of 2.885 percent.
Economic data at 8:30 a.m. ET is expected to show weekly jobless claims rose to 232,000 from 230,000 a week earlier.
Among stocks, Tesla was down 1.4 percent in premarket trading after the electric automaker said spending could rise in 2018.
Twitter rose 11.8 percent after it reported its first quarterly net profit and topped Wall Street targets as video ad sales rose.
Yelp fell 11 percent after a host of brokerages cut their price targets on the consumer review website operator's stock following quarterly results. (Reporting by Tanya Agrawal; Editing by Saumyadeb Chakrabarty)