* Futures down: Dow 77 pts, S&P 7.25 pts, Nasdaq 13.75 pts
By Sruthi Shankar
March 1 (Reuters) - U.S. stock index futures pointed to a third consecutive session of falls for Wall Street on Thursday, with sentiment weighed down by nerves ahead of Federal Reserve chair Jerome Powell's second round of congressional testimony.
The testimony, due at 1500 GMT, follows Powell's first appearance in Congress on Tuesday, which did little to cool market fears that his arrival at the Fed could see it deliver more U.S. rate rises than previously expected this year.
Wall Street ended a turbulent month dominated by worries over rising interest rates and bond yields on Wednesday, with the S&P 500 down for the first time in 11 months.
That was its longest winning streak in monthly terms since 1959 and analysts and traders cautioned that much of the turbulence this week may stem from market positioning as much as a substantial change of tack by Powell.
"Having sat through a prolonged period of incredibly low volatility across virtually all asset classes for the best part of two years, February will be best remembered for when volatility finally returned to markets," Deutsche Bank strategist Jim Reid wrote in a note to clients.
The CBOE Volatility index, the measure of short-term stock market volatility on Wall Street, was last at 20.72 - its highest in a week.
By 6:41 a.m. ET, Dow e-minis were down 77 points, S&P 500 e-minis lost 7.25 points and Nasdaq 100 e-minis fell 13.75 points.
Another potential source of concern will be the latest reading on personal consumption expenditure, the central bank's favored gauge of inflation, which is expected to have increased 0.3 percent on a core-basis in January after a 0.2 percent gain in December. That data is due at 8:30 a.m. ET.
Reports on weekly jobless claims and ISM's index of national factory activity are also expected on Thursday.
Fed New York head William Dudley is due to speak on trade and globalization at a Central Bank of Brazil event.
Among stocks, Novavax soared nearly 30 percent after the vaccine developer reported positive results from early-stage study of influenza vaccine.
Best Buy jumped around 5 percent after it reported for the fourth quarter, recovering from falls overnight due to the U.S. consumer electronics retailer's announcement of 250 small mobile phone store closures.
Shares of steel companies AK Steel and US Steel Corp gained on signs of a possible major trade announcement by President Donald Trump, who has been considering imposing hefty tariffs on imports of the metals from China and other countries. (Reporting by Sruthi Shankar in Bengaluru)