"Her strident dovishness causes us to lower our projected number of rate increases this year to possibly one in September or even as late as December," Citigroup economist William Lee said in a note that echoed the widely held Wall Street sentiment after the central bank chief spoke.
Yellen's comments reflected a variety of fears, much of them centered on the global landscape.
As David Rosenberg, chief economist and strategist at Gluskin Sheff, pointed out, she used the word "global" 11 times, which was seven more than her speech to Congress in February, and "uncertainty" 10 times, up from three in the last speech.
The remarks came amid a deteriorating economic picture, though a U.S. recession still is considered unlikely by most economists. The Atlanta Fed now expects gross domestic product to gain just 0.6 percent in the first quarter, down from about 2.7 percent in early February. The Atlanta Fed's GDP-based recession indicator shows just a 10 percent chance of recession, though that has not been updated since Feb. 4.
"Whenever a central banker is uncertain, rest assured that the only certainty is that he or she does nothing," Rosenberg said in his daily report for clients. "That was the message from Yellen's speech. Rate risk is off the table, but the reasons for it — a lack of growth visibility — are why investors did not bid up stocks even more so despite her overt dovish tone."