While I don't share Citron Research's price target of 50 cents a share, $8 and especially $9-plus appears to me as even more ridiculous. Yes, I get sales are improving, and I truly want the company to succeed, and I like the technology, but the forward estimated earnings don't support the current price. Part of the hidden problem is the price isn't even the price for long.

According to WSJ.com, the float is 110.55 million out of 117.03 shares outstanding. At $7, a 1% ownership will cost $7.7 million. You won't own 1% for long though because the company has issued millions of stock warrants as an enticement for the many equity raises over the years.

In a little more than a month, almost 11 million convertible Series C preferred stock becomes convertible. When converted, it will dilute every shareholder by 9.4%, and you can bet the shares will become converted. Air Liquide Investissements paid $2.59 million for an investment worth over $80 million.

If that were the only expected dilution shareholders face, it may be palatable, albeit that's only the next significant date for what is likely to be a rapidly expanding number of shares available in the float.

The big question for investors to ask is what's the potential payoff if the company breaks free and becomes profitable? Next year's estimated earnings are 5 cents a share. If we adjust for likely dilution, it becomes closer to 3 cents.

If the stock were at $3, the forward earnings multiple would about 100; at $6, the multiple would be 200. That compares to Tesla Motors (TSLA) at 56, Amazon (AMZN) at 83, Google (GOOG) at 19 and Apple (AAPL) at 11. Historically, stocks with multiples over 20 underperform those whose multiples are less than 20. If you're buying Plug Power above $8, you're paying over 200.

That means it will take 200 years of earnings to pay for one share if the company is able to reach estimates for 2015 while not needing to raise more capital.

The company is burning through cash at a rate that one would expect at least one more capital increase (i.e. further dilution) if the company stays on track and doesn't hit a pothole on the way to becoming profitable.

If you're an active day trader, Plug Power is a superb trading vehicle with loads of volatility; however, if you're an investor, ring the register and take some profit because you will have another chance to buy much lower.

At the time of publication, Weinstein is short Plug Power.

Follow @RobertWeinstein

This article is commentary by an independent contributor, separate from TheStreet's regular news coverage.

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