Apple, already the world's most valuable company, has reached the $600bn (£378bn) level for the first time.
Only one other company has been worth that much - Apple's old sparring partner Microsoft.
The electronics giant reached that valuation for 13 trading days around the turn of the millennium, at the peak of the technology stock mania.
At its highest level, on December 30 1999, Microsoft's valuation was $619bn. It's now worth $260bn (£163.76bn).
General Electric came just short of reaching a $600bn valuation in August 2000.
Apple shares hit $644 (£405) yesterday.
Apple's stock is up 59% since the start of the year, an indication that investors are catching up to what analysts have been saying for a while: despite its enormous market capitalisation, Apple's stock has been undervalued relative to its enormous profits.
The rally has also been fuelled by the report of another blow-out holiday quarter and the announcement that Apple will start putting its $97.6bn (£61.47bn) cash hoard to use this summer by paying a dividend and buying back shares.
Apple's market capitalisation hit $500bn (£314.9bn) on February 29.
That, in itself, was a rare achievement: only five other US companies have ever been worth that much.
Many analysts think Apple can get there, though.
Last week, Brian White of Topeka Capital Markets was the first to set a stock price target of more than $800 (£503), with a goal of $1,001 (£630.48). That target implies a market capitalisation of $932bn (£587.02bn).
Mr White believes Apple will expand its reach this year by starting to sell the iPhone through China Mobile, that country's largest phone company, and by launching a TV set.
Apple has not confirmed either piece of speculation.