Maybe it's the return of bubble mania, but shares of an outsize number of tiny, no-name companies have caught fire lately, and that has some urging caution.

The ones burning up the charts the past month aren't big-cap names, but little-known concerns like Industrial Services of America ( IDSA), up 806% to $40; Vaso Active Pharmaceuticals ( VAPH), up 309% to $36; and Unifab International ( UFAB), up 660% to $10.30.

Trading, meanwhile, in these small-cap Nasdaq stocks has been frenetic, with the demand far outstripping the relatively few shares each company has issued.

On Monday, for instance, 9 million shares of Industrial Services changed hands, even though the Kentucky trash-hauling company has just 900,000 shares available for trading. In other words, traders effectively churned the stock's entire float 10 times in a single day.

The hyperactive trading has been egged on by feverish postings on stock message boards urging investors to buy. Some of the stocks also are being touted in email alerts and newsletters that are favored by daytraders.

The buying doesn't seem based on fundamentals, because most of the companies are either losing money or marginally profitable. In the case of Vaso Active, a Massachusetts company that claims to have a miracle treatment for athlete's foot, there's been more hype than sales to point to.

Rather, what's drawing traders to these no-name moon shoots is the fact that they all have very few shares available for trading, which makes them highly volatile.

"It doesn't take a lot to move these stocks," said Satya Pradhuman, Merrill Lynch's director of small-cap research.

A number of the companies have announced stock splits the past few weeks. That could explain some of the interest, although several market observers discounted it as a major factor.

Some investors no doubt are hoping to catch lightning in a bottle and believe tiny stocks like Vaso Active and Industrial Services can be the next Taser International ( TASR), undoubtedly the most famous low-float screamer of postbubble Nasdaq. But at least fans of the stun-gun manufacturer can point to sharply higher revenue and net income as some justification for their exuberance.

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