Indeed, currency traders appear to have interpreted Yellen's remarks to Congress as hawkish, helping push the dollar to a six-week high against the euro.
Attention meanwhile turned to the European Central Bank, which kept interest rates unchanged, as expected, but investors looked for comments on Greece by ECB President Mario Draghi.
Read MoreWho'd be a central banker? Draghi set for tough time
Draghi said the ECB continues to act as though Greece will remain within the euro and the central bank has decided to raise emergency funds to Greek banks by 900 million euros.
The Eurogroup also released a statement saying "we reached today a decision to grant in principle a 3-year ESM stability support to Greece, subject to the completion of relevant national procedures."
On the data front, U.S. jobless claims data came in better than expected at 281,000. Analysts expected claims to come in at 285,000.