The Nasdaq Composite Index briefly crossed the 3,000 mark Wednesday for the first time in 12 years, boosted by the European Central Bank's action to increase liquidity in the euro zone financial system and a better-than-expected revision to the U.S. quarterly economic growth.

Investors' risk appetite was augmented by the European Central Bank flooding the financial system with more than half a trillion euros of cheap loans earlier this morning. Also adding to the positive sentiment was an 0.2 percentage point upward revision to U.S. fourth-quarter gross domestic product, which puts the U.S. economic expansion in the last three months of 2011 at 3 percent.

The Nasdaq crossed the psychologically significant threshold early Wednesday, gaining 13.35 points, or 0.45 percent, to 3,000.11.

However, the glory was short lived.

As Federal Reserve Chairman Ben Bernanke began his testimony before Congress at 10 a.m., the Nasdaq reversed early gains and plunged 29.18 points.

The Nasdaq, currently down 0.51 percent, at 2,971.67, has gained 14.3 percent in value this year. By comparison, the Dow is up 6.1 percent in 2012, while the S&P 500 has gained 8.63 percent so far this year.

The milestone for the tech-heavy Nasdaq index came a day after the blue-chip Dow Jones Industrial Average celebrated its big rally, closing above 13,000 on Tuesday for the first time since May 2008.

Apple's market value topped $500 billion, a level that few companies have reached and even fewer maintained. Its stock is currently up 1 percent, or $5.39, to $540.99 a share.