Internet stocks tumbled Monday in an early post-holiday sell-off - signaling what some analysts called a turning point.

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. 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.