PALO ALTO, Calif. (CNN/Money) - On a day when nearly everything's down, I like to look at what's up. It tells you what investors have to have, even when "the market" is screaming Sell!

The answer for Monday: Amazon, Yahoo!, eBay and a handful of the other strongest "e-commerce" stocks.

What's up with that?

Yahoo!, for example, is already worth about 88 times Wall Street's estimates of 2003 earnings. It is so highly valued that CEO Terry Semel has shown through his actions his opinion of Yahoo! stock twice in the last week.

First he used it to buy paid-search supplier Overture Services.

Then Semel exercised and sold 500,000 options to buy Yahoo! stock, netting himself a cool pre-tax $11 million.

But the market is showing, as it did before the early-2000 crash, that it just doesn't care about top-ticking signals by CEOs. What it cares about is that e-commerce is in vogue again. And with the momentum goes stock purchases, valuation be damned.

It's worth a word about the very expression "e-commerce."

Back in the late 1990s I repeatedly opined that there was no such thing as an Internet stock. My assertion was that every industry would adopt the best attributes of the Web and that eventually there'd be no such thing as a "pure-play" Internet stock.

I think I was mostly right. Distributors like Cardinal Health laughed at the notion that online market makers could "disintermediate" them. And they were right.

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The strongest financial institutions today, like global power Citigroup or retail banking heavyweight Wells Fargo, haven't been done away by the Web. They're using it heavily.

BUT -- and you knew there had to be a but -- companies like Amazon, Yahoo! and eBay are unique in the sense that nearly all their business is Web-based, they continue to benefit either from scale of their businesses or increased use of the Internet, and they are damned profitable.

So the businesses roll along and the stocks charge up a hill. Are they worth their multi-billion-dollar valuations? Of course not.

But are you going to short the gravity defiers that go up when the trend is down? Good luck.

SCO Group Note also the powerful surge in shares of SCO Group (SCOX: Research, Estimates), up 15 percent in late-day trading on Monday. SCO is a litigation vehicle for some clever executives in Utah who are attempting to extract a toll charge for many users of Linux, the open-source operating system, around the world.

Many thought the threats empty. But on Monday SCO announced its licensing program, explaining how it will attempt to collect the toll. Give the stock's surge, the market seems to think there's something there -- for now, anyway. For more, read my recent article on SCO in Fortune.

Silver Lake And in one last instance of the rich getting richer, take note of yet another score for Silver Lake Partners, the buyout group that on Friday sold Crystal Decisions to Business Objects for more than $800 million.

Crystal, formerly a unit of disk drive maker Seagate Technology, had planned an IPO. But French software maker Business Objects bought it instead, making for a potentially quicker payout to Crystal's shareholders, the largest of which is Silver Lake. Wall Street cheered the deal, presumably rewarding Business Objects for a shrewd pick-up. Its stock was up as much as 15 percent Monday.

Adam Lashinsky is a senior writer for Fortune magazine. Send e-mail to Adam at lashinskysbottomline@yahoo.com.

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