Tuesday was a landmark day for Apple, as company stocks hit $644 a share, which at that price makes the company worth $600.4 billion. Apple is only the second company, behind rival Microsoft, to ever reach the $600 billion mark.

After Tuesday’s high, Apple stock dropped nearly six points, putting the company’s value back below $600 billion for the time being. Microsoft is the only other company to surpass this landmark when the tech giant reached $619 billion in 1999 during the tech boom. General Electric (GE) fell just short of $600 billion in 2000.

Microsoft’s valuation has fallen quite drastically since its 1999 peak. Today the company is worth about $260 billion. Apple stocks, on the other hand, are up 59 percent this year, amid record profits and the release of the new iPad 3.

Apple plans to pay its shareholders a dividend this summer, as well as buy shares back, using a $97.6 billion stash of profits.

Analysts believe Apple stock has yet to reach its peak. Brian White, analyst at Topeka Capital Markets, was one of the first analysts to publicly set price target of $800 and a peak goal of $1,001 per share. If Apple stocks reach this peak level, it would represent a market capitalization of $932 billion, surpassing Microsoft’s valuation in 1999 by a significant amount.

Not everyone believes Apple stocks are on the rise. Walter Piecyk, BTIG Research analyst, believes Apple’s profit margins aren’t sustainable. He also states the iPhone upgrade policies make it too difficult for people to upgrade to the next model. Apple’s quarterly report released in two weeks will admittedly not reflect his prediction, but subsequent quarterly reports will reflect slower or declined growth.