The Nasdaq powered to a fresh record Thursday, easily topping the prior all-time high in a broad rally that withstood signs that a Greek debt default could be moving closer.
The Nasdaq Composite Index surged 68.07 points (1.34 percent) to 5,132.95, more than 25 points above the May 27 record close. The Nasdaq also set a new intraday record of 5,143.32, about 11 points more than the prior high set in March 2000, shortly before the dotcom crash.
The Dow Jones Industrial Average jumped 180.10 (1.00 percent) to 18,115.84, while the broad-based S&P 500 gained 20.80 (0.99 percent) at 2,121.24.
Analysts attributed the rally largely to Wednesday's Federal Reserve policy announcement and pledge from Chair Janet Yellen that the US central bank will raise interest rates from near-zero levels only gradually.
"The key takeaway is that the Fed will move more slowly than they previously said," said Chris Low, chief economist at FTN Financial.
The surge came despite a warning from Greek Finance Minister Yanis Varoufakis that "an accident" in the bitter dispute between Greece and its EU-IMF creditors over unlocking vital bailout cash for Athens was drawing "dangerously close."
That came as International Monetary Fund chief Christine Lagarde said progress in negotiations with Greece required "adults in the room" in an apparent swipe at Greek officials.
Low said he was "a little surprised" at the market's shrugging response to Greece.
"Maybe we fully priced in Greece leaving the euro," he added.
Large tech stocks to gain included Apple (+0.5 percent), Amazon (+2.7 percent) and Google (+1.4 percent). Biotech stocks, such as Celgene (+4.2 percent) and Biogen (+2.7 percent), were also strong.
BioMarin Pharmaceutical surged 12.2 percent after releasing positive clinical results of its Vosoritide medication for treating human dwarfism.
Fitbit, the company known for wearable devices promoting healthy lifestyles, saw its shares surge 48 percent to $29.68 following the biggest initial public offering this year for the tech sector. The IPO, at $20 a share, raised up to $732 million. The market value for Fitbit was some $4 billion based on the IPO.
But software and networking giant Oracle fell 4.8 percent after reporting net income for the quarter ending May 31 of 78 cents per share, nine cents below analyst expectations. The company said results were marred by the strong dollar.
Bond prices fell. The yield on the 10-year US Treasury rose to 2.34 percent from 2.32 percent Wednesday, while the 30-year advanced to 3.13 percent from 3.09 percent. Bond prices and yields move inversely.