Investors who gorged themselves on technology stocks in the spring--only to lose their appetites this summer--now have decided they've had their fill of initial public offerings as well.

Driven down by faltering tech stocks, the IPO market has gone from feast to fen-phen in the last two weeks. Investors who had gobbled up every new stock Wall Street served them for months and bid up prices of new issues at an unprecedented rate suddenly are picking over prospectuses like the last of the summer fruit.

While demanding--and getting--discounts on some IPOs and encouraging other offerings to be pushed to the back burner, they're nonetheless paying top prices for the few prime stocks coming to market.

Yesterday investors spurned the shares of Blockbuster Inc., which already has lived up to its name in the video rental business, but scrambled to buy the stock of Red Hat Software Inc. on no more than the hope that it could become the biggest thing in computer programming since Microsoft Corp.

Red Hat's stock jumped from $14 a share to $52.06 1/4 on the first day of trading--producing the instant profits that were common earlier in the year but have become increasingly rare since early July.

Red Hat sells a computer operating system called Linux that is considered the first viable competitor in years for the Microsoft programs that control the inner workings of computers. Originally set to sell for $10 to $12 a share, Red Hat's IPO was boosted to $14 a share when underwriters set the price Tuesday night. The stock then soared when trading started yesterday morning.

But Blockbuster, which had hoped to sell its IPO for $16 to $18 a share, put the issue on the market at $15 a share yesterday morning and it was still trading for $15 a share at the end of the day. Viacom Inc. which bought Blockbuster in 1994, is spinning off the business to the public after finding it does not fit in with its movie and broadcasting business.

The reaction to the two stocks shows what's happening in the IPO market, said Tom Taulli of Internet.com, a financial information Web site.

"Unless you are in a big industry with huge market potential--like today with Red Hat or last week with Internet Capital Group--you're in trouble," said Taulli, the author of "Investing in IPOs."

Red Hat's success "has zero to do with the IPO market," said David Melow of IPO Financial Network in Milburn, N.J. What it shows, he said, is that with many of last spring's hot technology IPOs now selling for less than half their peak prices, investors are being extremely cautious about what new issues they buy.

The perception only a few months ago was that the IPO market was hotter than it has ever been. "The first seven months of this year has just been off the map," said Jay Ritter, a University of Florida finance professor who studies such things.

In the first seven months of the year, Ritter said, there were 55 IPOs that doubled in price on their first trading day. Compare that with the number of IPOs--a mere 39--that doubled over the 24-year period before 1999.

"The IPO market has always been oversensitive to market movements," Ritter explained, "and the Internet IPOs have been hypersensitive even by the normal excesses of the IPO market."

With the slide of benchmark Internet stocks such as America Online Inc. of Dulles, which is down from its high of $167.50 a share to $92.37 1/2 as of yesterday, Net companies that went public earlier in the year have fallen into a new pattern: Instead of soaring right after going public, they are diving.

It was clear the bloom was off the Internet rose by last week, when 1-800-Flowers.com went public in an offering that was expected to blossom because the company is concentrating on selling flowers over the Net. Instead it wilted instantly, falling from $21 a share to $18 on the first day of trading and drooping to $14.31 1/4 yesterday.

Similar fates have befallen most of the Internet companies in the Washington region that have gone public in the last few months. Hardest hit has been ValueAmerica.com, the Charlottesville Net retailer, which went public at $23 a share in April, jumped to $55 a share and has fallen to $10.93 3/4. Shares of CAIS Internet of Washington, Careerbuilder.com of Reston and USInternetworking of Annapolis all have fallen below their original offering price in the last few weeks.

One factor in the Internet IPO slump is simply oversupply, analysts agree. When the market was overheated, so many Net companies started making plans to go public that they flooded the market. In the first eight months of the year, 312 companies raised $34.8 billion in IPOs, setting a pace that will easily exceed last year's $36.8 billion IPO production and could match the record $49.9 billion of 1996, according to Thomson Financial Securities Data Corp.

Though demand for IPOs has been dwindling along with tech stock prices, the supply has continued to build. By this week, 46 companies had completed the regulatory review process and were scheduled to sell their shares.

Some are holding to that timetable, such as Mortgage.com, a Florida online lender, which sold stock yesterday for $8 a share rather than the $10 to $12 it had hoped for. Others put their IPOs on hold, among them Garden.com, which purveys gardening gear and advice, and OpenSite Technologies, a maker of software for online auctions.

CAPTION: Slowing Down (This chart was not available)