Internet stocks tumbled yesterday in an early post-holiday sell-off--signaling what some analysts called a turning point in what has so far been a phenomenal year for just about every company associated with the words "dot-com."

Hit particularly hard were Web retailers, or "e-tailers," such as Amazon.com, which slipped 9.9 percent, to 81 1/8, and eToys, which plummeted 16 percent, to 25-15/16. Shares of America Online, which hosts one of the largest Web shopping malls, and auction house eBay also fell, although both stocks recovered somewhat from early-afternoon dives.

Bright projections that Web Christmas sales would be triple that of last year had boosted e-tail stocks to new highs in November. And by most projections, the predictions may prove accurate. Forrester Research now says it expects holiday revenue to top $4 billion, while others peg it closer to $6 billion.

But now, many investors are worried about how the companies are handling the windfall, analysts said. Online stores recently have been hit with complaints of shipping delays and technological glitches that have made shopping on the Internet more of a headache than a convenience.

"People are starting to be more discerning" about picking e-tail stocks, said David Readerman, director of Internet strategy at Thomas Weisel Partners. "It's not going to be enough for them just to have traffic on their site. They are going to have to transform the hits into revenues and to deliver the products they promise.

"It's going to be much tougher and more of a shakeout to win Wall Street in 2000," he added.

For the past month, irate visitors to e-commerce sites have complained of stock and delivery problems. Indeed, an Andersen Consulting study released last week found that about one-quarter of online transactions go awry for various reasons, ranging from site crashes to items being out of stock.

Steve Weinstein, an Internet analyst with Pacific Crest Securities in Portland, Ore., said customers have yet to develop the same tolerance for e-tailers that they have for traditional retailers.

"If you're at a store and stuck two hours waiting in line, you might complain but you'll continue to go to the store. But if there's a hiccup online, people tend to be a little less forgiving," he said.

Toys R Us's online store has been among the most troubled this season. Earlier this month, the company e-mailed customers saying it would not be able to fill their online orders by Christmas and offered $100 gift certificates for use in its stores. CDNow.com, Patriot Computer, known for its popular Barbie- and Hot Wheels-branded personal computers, and others flashed messages on their sites warning potential buyers that they could not guarantee Christmas delivery.

Still, many of their stocks had remained high--helping boost the Nasdaq composite index, the Dow Jones industrial average, and the Standard & Poor's 500-stock index to record peaks on the day before Christmas Eve.

Yesterday, though, e-tail stocks tumbled even as shares of traditional bricks-and-mortar retailers such as Wal-Mart Stores rose. Stock performance was mixed when the market closed on typically light trading during the week between Christmas and New Year's: The Nasdaq composite index rose 5.94 to close at 3975.38, just past its previous record of 3969.44. Meanwhile, the Dow dipped 14.68, to 11,391.08. The S&P 500 inched up 1.25, to 1457.09.

As for the Internet retailers, some analysts said they don't expect their stocks to jump back any time soon. "The technology sector itself is kind of 'blah' now. There is nothing to push them up after the crazy holiday sales," said Alan Mak, an analyst with Argus Research.

But Pacific Crest's Weinstein said his longer-term forecasts continue to be spectacular: "I think at this point we just broke the 1 percent of the-people-who-shop-online barrier. We've just scratched the surface of these companies. They can't all be winners but there's tremendous growth ahead."

Still, before they can even think about how to tackle a new year of birthday and Christmas sales, harried e-tailers must face a more immediate problem likely to cut in to their bottom line: The current onslaught of post-holiday returns, exchanges and refunds.

CAPTION: Internet Downturn (This chart was not available)