As the rumored roll-out of the latest iPhone looms next month, investors seem bullish on Apple.

The tech giant’s market value now exceeds $623 billion, breaking the record set by Microsoft during the halcyon days of the late 1990s dotcom bubble.

That said, once adjustments for inflation are factored in, Microsoft still holds the record — its peak value of $621 billion is the equivalent of $854 billion today.

Regardless, Apple’s stock has risen nine percent this month in the run-up to the launch of the iPhone and, possibly, a smaller version of the company’s popular iPad. Overall, shares of Apple have risen 64 percent in 2012, closing Monday at a session high of $665.15.

If you’re thinking about taking plunge and adding some Apple stock to your portfolio, Howard Silverblatt, senior index analyst at S&P Dow Jones Indices, advises caution.

“If you play the quick trade, be careful,” he said. “If you are an investor, check the fundamentals and business plans, and avoid the hype in your decision.”

[Reuters]