Apple is now the highest valued company in the history of Wall Street after the tech giant's stock worth hit $623.5 billion at the market's close on Monday.

That market value beats Microsoft Corp's old record of $613 billion, which was set in 1999 during the Internet boom. Adjusted for inflation, Microsoft was worth about $850 billion then.

Many analysts believe Apple can still go higher.

The company's stock has been rising because of the upcoming iPhone 5 and a possible new "mini iPad."

"This time around, investors are a little bit smarter across the board," Wedbush Morgan's Scott Sutherland said. "They don't want to be caught not involved in the stock on this next iPhone launch."