Powell said U.S. central bankers are moving carefully on policy now after aggressive rate hikes last year to give time for tighter conditions to slow the economy and inflation.

MARKET REACTION:

STOCKS: The S&P 500 initially pared declines before reversing course and was last down 0.5%BONDS: The U.S. Treasury 10-year yield moved higher after a brief decline and was last at 4.97%.

FOREX: The dollar index added to losses initially before paring declines and was last down 0.17%.

COMMENTS: MICHAEL BROWN, MARKET ANALYST, TRADERX, LONDON

"Some decent USD downside seen, perhaps more than one would expect.

"Quite clear that the market is reading into Powell's comments on tighter financial conditions potentially leading to the tightening cycle being done and dusted. Obviously other FOMC officials have said similar, but hearing so 'from the horse's mouth' gives the statement extra credibility."

MICHAEL JAMES, MANAGING DIRECTOR OF EQUITY TRADING AT WEDBUSH SECURITIES IN LOS ANGELES

"I don't think he's un-muddied the waters so much. The tone was a bit more dovish than other Fed officials recently. He addressed recent tightening in financial conditions as significant. He also talked about elevated geopolitical tensions posing risks to global economic activity.

"On the other hand he also didn't remove the higher for longer bias as inflation has not yet come down to a level where the Fed is likely more comfortable.

"It's hard to make too much of a determination about what happens with knee jerk reactions immediately after any type of Fed comments ... There's always going to be traders reacting quickly in both directions so trying to make any type of broad based assumption within 10 minutes of any fed official statements is a touch premature."

CHRIS ZACCARELLI, CHIEF INVESTMENT OFFICER, INDEPENDENT ADVISOR ALLIANCE, CHARLOTTE, NC

"Powell continued to leave optionality open for the Fed, in terms of future rate hikes, but did nothing to change the narrative that the Fed will keep rates unchanged at their next meeting and is relatively likely to keep them unchanged for the rest of this year as well (e.g. unchanged in December meeting as well)."

(Compiled by the Global Finance & Markets Breaking News team)