US Treasuries rose, pushing yields on the benchmark 10-year bond seven basis points lower to 1.99 per cent.
Yellen suggested Fed policymakers "need to see continued strength in the data and reasonable confidence that they will be able to move back to their 2 per cent objective over the medium term," Eric Green, head of US rates and economic research at TD Securities USA, told Bloomberg. "That is being looked at by the bond market that that may put a September hike out of the question."
In afternoon trading on Wall Street, the Dow Jones Industrial Average rose 0.40 per cent, while the Standard & Poor's 500 Index moved 0.09 per cent higher. The Nasdaq Composite Index slipped 0.07 per cent.
Earlier in the session the Dow climbed to a record 18,212.08, while the S&P 500 hit a record 2,116.50.
"We have some more time where rates are not going to change dramatically over the near-term," Bill Schultz, chief investment officer at McQueen, Ball & Associates in Bethlehem, Pennsylvania, told Bloomberg. "The market's interpreting it as a continuation of policy until proven otherwise - going to need to see continued evidence, job growth, inflation or economic growth picking up before they're going to change their forward guidance."
The latest data were solid indeed. The S&P/Case Shiller composite index of 20 metropolitan areas climbed 4.5 per cent in December from the prior year.
Separately, Markit's preliminary reading of its purchasing managers index for the service sector increased to 57.0 in February, up from 54.2 in January.
To be sure, the Conference Board's consumer confidence index fell to 96.4, the lowest since September, from an upwardly revised 103.8 in January.
Gains in shares of Home Depot and those of JPMorgan Chase, last up 3.3 per cent and 2.4 per cent respectively, propelled the Dow higher.
Home Depot shares climbed after the company reported better-than-expected quarterly earnings and offered a more upbeat full-year outlook than anticipated. It also announced an US$18 billion share buyback and boosted its dividend.
In Europe, the Stoxx 600 Index finished the session day with a 0.6 per cent increase from the previous close, after euro-zone finance ministers agreed to extend Greece's bailout program. France's CAC 40 Index rose 0.5 per cent, while Germany's DAX gained 0.7 per cent. The FTSE 100 Index added 0.5 per cent to close at a record high.
Greece's ASE Index jumped 9.8 per cent. The market had been closed on Monday for a holiday.