Updated from 1:22 p.m. EDT

Shares of IBM ( IBM) sagged $3.98, or 4.6%, to $83.35 a day after the company admitted the Securities and Exchange Commission is investigating some of its accounting from 2000 and 2001.

Late Monday, Big Blue said the SEC wants more information about its recognized revenue for certain customer transactions. IBM said it believes the investigation is related to a separate SEC investigation of a customer of IBM's retail store solutions unit, which sells point-of-sale products.

This morning, market watchers were divided on the takeaway: Some cast the news more as a point of concern than cause for immediate worry. Others said it was a far more serious matter than was portrayed.

"I think right now the stock is holding in because several analysts came out today and said this is not a significant event and will wash away. I couldn't disagree more," says Richard Williams, an analyst at Summit Analytic Partners, an independent research firm. "I think it threatens a crisis of confidence in the stock and the market.

"Not a whole lot has been said about the scope and scale of the investigation," he adds. "But if there's any hint that it goes beyond retail, the stock will get clobbered on that alone, I think."

Williams, who holds a small short position in IBM, blasted the company's first quarter results in April, arguing IBM would have dramatically missed earnings estimates if it hadn't been saved by a weak dollar. He holds up the first-quarter numbers as an "egregious example" of the company's tendency to use one-time gains to meet Wall Street expectations, following on past controversies over how the booking of asset sales and gains on its giant pension fund factored into the bottom line.

And if IBM has to rely on accounting legerdemain to meet estimates, Williams argues, it no longer deserves to trade at a premium to its growth rate. Based on Monday's close of $87.33, the stock changes hands at a P/E of 20 for this year, while consensus estimates imply earnings growth of just under 10% this year. Next year's P/E is at 18, compared with an earnings growth outlook of a little above 10%.

Other analysts focused on the terse character of IBM's release. "We have our doubts that IBM is telling the whole story," says a note out today from John Gavin, head of research firm SEC Insight. "From IBM's word choice and limited follow-on guidance, our opinion is that IBM assessed the matter as material and thus felt compelled to disclose, but did so in a manner that simply meets the threshold for disclosure -- not openness. We've seen this manuever before from the likes of Qwest and EDS. Both companies previously said the SEC had contacted them regarding a 'customer' and both companies initially downplayed matters."

"We think that is happening here," continues Gavin. "Let's not forget that manipulations of revenue recognition -- particularly among tech companies -- has been a strong SEC red flag for years now and the SEC has challenged the company on this before."