Stock futures on all three major U.S. stock markets traded in positive territory, with Dow Jones industrial average futures up over 80 points in early London trade.
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Investors have a slew of earnings to digest. Goldman Sachs,Citigroup, Blackstone, Charles Schwab, UnitedHealth, eBay and Phillip Morris are among the firms reporting second-quarter earnings before the market open.
Goldman Sachs posted quarterly earnings that fell sharply from the previous year, hit by a large litigation charge.
Citigroup delivered quarterly results that topped analysts' expectations on both the top and bottom lines, for the largest quarterly profit in 8 years.
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Google, Schlumberger, Mattel, Advanced Micro, Celanese and Cintas are expected to report after the closing bell.
U.S. weekly jobless claims came in at 281,000, better than the 285,000 estimate.
The U.S. 10-year treasury yield held near 2.38 percent, with the 2-year at 0.67 percent.
The dollar gained about half a percent as the euro fell below $1.09 to an eight-week low.
The Philadelphia Fed survey and NAHB homebuilders' survey are due at 10 a.m.
In addition to the earnings and data, markets await Yellen's testimony to the Senate Banking Committee. On Wednesday, Yellen reiterated recent comments that interest rates are likely to rise this year.
"These tend to go largely the same way as yesterday's event but should still be monitored closely for any surprises, of which there were none yesterday," Craig Erlam, senior market analyst at currency trading firm Oanda, said in a note.