The tech-rich Nasdaq added 22.34 points (0.78 per cent) at 2,869.88, the highest close since December 2000, when it was plummeting as the dot-com bubble famously burst, plunging the country into recession.
Riding news that the Fed would not raise ultra-low interest rates, the Dow Jones Industrial Average also surged, adding 95.59 points (0.76 per cent) to finish at 12,690.96.
The broad-market S&P 500 advanced 8.42 points (0.62 per cent) to 1,355.66.
The blue-chip Dow and the S&P 500 finished at their highest levels since 2008, in May and June, respectively.
"US stocks moved solidly higher on the day, after receiving a nice afternoon jolt from the comments of Fed chairman Ben Bernanke in the inaugural post-policy meeting news conference," Charles Schwab analysts said in a client note.
The Fed, citing the economy's only "moderate" recovery, also kept the door open for more economic stimulus, while saying its current $600 billion program would be allowed to run its forecast course through June.
Helping to underpin the market, on the ninth day of a solid rally, was a report that durable goods orders had risen 2.5 per cent in March, a sign that US industry continues to expand and companies are investing in and upgrading equipment.
"Today's report brought two important positive signals -- the rise in the March core component and a significant upward revision of the February figure," said analysts at Natixis.
"Indeed, the 'core' nondefense ex-aircraft capital goods orders which are supposed to be an indicator of the business spending on equipment and software got back to a strong upward trend observed at the end of 2010."
Among companies reporting earnings, shares of oilfield operator Baker Hughes leaped 4.3 per cent to $77.28 after its first-quarter net income beat estimates handily.
Boeing rose 0.7 per cent to $76.12 after posting better-than-expected quarterly earnings.
Corning shares surged 2.3 per cent to $21.08 on stronger-than-expected revenues from sales of glass for the huge LCD television and computer monitor industry.
Online retailer Amazon jumped 7.9 per cent to $196.63 dollars as investors shrugged off disappointing earnings and focused on higher sales forecasts.
The bond market slumped. The yield on the 10-year Treasury rose to 3.37 per cent from 3.32 per cent late Tuesday. The 30-year Treasury yield climbed to 4.46 per cent from 4.40 per cent.
Bond yields and prices move in opposite directions.
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