Yellen, who spoke after the market closed, may have slightly recalibrated expectations for a rate rise, by saying she personally anticipates a hike this year.
Traders had hoped the speech would clarify the central bank's position on rate hikes, after last week's FOMC meeting and a week of volatile markets.
Read More Yellen nudges markets slightly on rates
The Fed chair said it would likely be appropriate to raise rates from near zero "sometime later this year," though the decision would continue to rely on economic data. In her comments last week, she had not identified herself as part of the group favoring rate hikes this year, but she had made a similar comment during the summer.
Dow futures traded about 210 points higher after briefly gaining 250 points, while S&P 500 and Nasdaq futures also indicated a higher open.
On the data front, the second revision for second-quarter GDP came in at 3.9 percent.
GDP was expected to show growth at 3.7 percent. Consumer sentiment is due to be released at 10:00 a.m.
The dollar gained and yields held higher, with the 2-year near 0.71 percent.
In Europe, the pan-European Stoxx 600 index (^STOXX) was about 3 percent higher Friday morning, helped by some recovery in auto stocks. In Asia, the Shanghai Composite (Shanghai Stock Exchange: .SSEC) index closed down 1.62 percent, while Japan's Nikkei (Nihon Kenzai Shinbun: .N225) finished 1.76 percent higher.
On the earnings front, BlackBerry (Toronto Stock Exchange: BB-CA) and Finish Line (FINL) both posted results before the bell.
BlackBerry—The handset maker lost an adjusted 13 cents per share for its latest quarter, 4 cents wider than estimates. Its revenue was well short of forecasts, and it projected "modest" sequential quarterly revenue growth for the rest of fiscal 2016.
Finish Line—The athletic apparel and footwear retailer matched estimates with adjusted quarterly profit of 57 cents per share. Revenue missed analyst forecasts, however, as same-store sales rose 1.5 percent.
In oil markets, Brent crude (Intercontinental Exchange Europe: @LCO.1) traded at around $48.28 a barrel, up 0.23 percent, while U.S. crude was at $45.23 a barrel, up 0.71 percent.
--CNBC's Patti Domm contributed to this report.
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