NEW YORK (TheStreet) -- Shares of Fitbit (FIT) were tanking 29.78% to $8.99 on heavy trading volume late Thursday morning after the company posted third-quarter revenue that missed analysts' expectations and issued a downbeat forecast.

"I think that everybody who wants a Fitbit has one," TheStreet's Jim Cramer said on CNBC's "Squawk on the Street" this morning, "I just think it's done."

Fitbit CEO James Park appeared on Cramer's "Mad Money" in early October and said the Charge 2 device is the number one best-selling fitness tracker on Amazon (AMZN).

But Cramer noted that channel checks at Pacific Crest Securities showed that sales had "dropped off a cliff."

"(Park) was refuting that with looking at how it's doing on Amazon. And that was obviously...completely inaccurate as a read on the company. But what it says to me is here's a man who obviously is not in touch with how his company is selling the product. This was not that long ago," Cramer added.

"This was less than a month ago, in a quarter where the numbers were falling hard. And he is quoting numbers from Amazon when the company's numbers, which I think obviously are broader than Amazon, were a dramatic shortfall. So I don't know what to make of it," Cramer stated.

He said that Park "has lost any credibility" and Cramer believes that Fitbit is "done."

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