Sometimes you can get a feel for that by checking the Insider Selling data on MoneyCentral. VerticalNet, again for example, has a truly long list of planned sales that include huge blocks held by prepublic investors. Lehman Brothers MBG Venture Capital Partners, for instance, filed on Feb. 10 to sell 1 million shares. Since the sale isn't listed among the completed transactions, it appears that this intended sale still hangs over the stock. At the least you should avoid buying shares of a stock like this until you can see that it has put in a firm base.
Any dip is likely to be followed by a lower dip.
Any rally is likely to be met by massive selling. A stock in this class needs to trend sideways for a while before it's safe to step in. I hope that you got out of any momentum stocks of this type that you owned before the recent carnage. But if you reaped the gains of holding this kind of stock in 1999, it's unlikely that you sold off everything in your portfolio that meets this description. I think the road back for a momentum stocks like Commerce One is likely to be long and rocky.