“Hey, don’t count out Google just yet,” says Charles Biderman, president of TrimTabs Investment Research of Santa Rosa, Calif.”It’s the most rapidly growing tech company around and as long as that’s the case, it’s going to sell at a premium.”

That’s his reaction to this week’s sell off in Google, which was sparked by some rating downgrades and bad numbers from rival Yahoo. In response, Google’s stock skidded Wednesday more than $22 a share or 4.75% to $444.90. It closed yesterday at $436.44.

Taking issue with the bears who contend that the stock – up more than 450% from its August 2004 offering price of $85 a share – is way ahead of itself, Mr. Biderman, who personally holds a stake in Google, argues it’s still worth owning at its current price and merits being bought on any pullbacks.

Some critics disagree, contending that the big decline has eliminated much of the go-go from Google. One is money manager Tom Postin of Los Angeles-based P &W Partners, who tells me, “The mood has changed, the momentum is broken, and the stock no longer looks invincible or that it’s headed to the moon.”

Interestingly, one analyst who provoked part of the selling, Standard & Poor’s Internet tracker Scott Kessler, who downgraded Google on Monday evening to a “sell,” is reluctant to say the stock’s meteoric 17-month rise is over. Why not? Because Google, he says, is “a really great business model with great execution and strong growth prospects.”

His glowing numbers tell the story. Last year, he reckons, Google earned $5.80 a share on gross revenues of $6.1 billion. That’s more than double 2004’s $2.75 a share on revenues of $3.2 billion. This year, the analyst again sees lofty gains, with earnings, factoring in option expenses, climbing to $7.62 a share on $10 billion in revenues.

So why is he urging investors to bail out of Google? Mr. Kessler points to some pretty notable risks that he says investors seem to be unaware of or really don’t care about. Among them:

* An absence of revenue diversification, with virtually all revenues coming from one source: Internet advertising.

* A lot of building competition, such as Microsoft, which will enter the fray this year with search-related elements; AIC/InterActiveCorp., owner of Ask Jeeves; News Corp.’s Fox Interactive Media, which owns My Space, a service that’s said to have accounted for more than 10% of all Internet advertising in November, andYahoo, which everyone underestimates.

* Google’s willingness to pursue lower margin businesses, such as providing wireless Internet access to the city of San Francisco, as well as to make big investments, which could detract from margins over the near term.

On another score, Mr. Kessler, who sees slowing growth in 2007, observes that 30% of all Google clicks could be fabricated from people paid to have a vested interest to goose the number of clicks. This, in turn, he points out, could affect Google’s advertising appeal.

On Monday Google announced the acquisition of a West Coast radio broadcaster for as much as $1.24 billion to help it automate ads into radio broadcasting. To Mr. Kessler, it was a negative sign in that it showed Google’s need to diversify beyond online search.

Meanwhile, a former Merrill Lynch Internet analyst, Henry Blodget, citing the threat of intensifying competition, recently entered the fray with a provocative forecast that Google shares could plummet to $100. No one would be happier if Mr. Blodget were right than the bloodied short sellers. All told, there are 8.2 million shares short.

In a related development, some Wall Street contacts suggest the Google sell-off also demonstrates the folly of Wall Street’s issuance of wildly ecstatic and make-believe stock price targets. In recent weeks, for example, the Street has bombarded investors with unbelievably high 12-month price objectives of $500, $540, $600, $800, and $2,000. These have come out of such firms as Goldman Sachs, Oppenheimer & Co., Bear Stearns, Piper Jaffray, and Caris & Co.

“It’s Wall Street at its irresponsible worst,” says Arnold Silver, a Los Angeles day trader, in commenting on these highly exuberant stock price targets. “Analysts,” he says, “are not supposed to tout stocks to generate additional commissions for their firms or please some large customers by promoting their big holdings, which is basically what I think happened here.”

Mr. Kessler is also critical of what he terms “the promotional and excessive Google forecasts.” In some cases, he believes, these are off-the-cuff projections that lack the support of any rigorous analysis.

The bottom line on Google? Mr. Silver may offer the best outlook. “If you enjoy Russian Roulette, buy Google now or sell it short. Either way, it invites a heart attack or a fast trip to the graveyard.”

dandordan@aol.com