NEW YORK ( TheStreet) -- The lithium ion battery makers A123 Systems ( AONE) and Ener1 ( HEV) may be similar, but the green energy stocks have hit a fork in the road. The stocks have been moving in different directions since both reported extremely weak first quarters.

Over the past month, shares of A123 Systems are flat, while Ener1 shares have declined 50%. There's one obvious reason for this: even as A123 Systems posted negative gross margin of 85% in the first quarter, it had already raised cash earlier this year in a secondary to push out a little further the cash burn issue.

Ener1, on the other hand, which took a huge $70 million write -down in the first quarter in throwing in the towel on its electric car market deal with Think Global, said during its earnings conference call that it will have to raise more money. Ener1 CEO said that given its shares price -- now at $1.30 -- it won't be doing a secondary offering. But even a private offering could include warrants that dilute existing shareholders by as much as 50%, said Wunderlich Securities analyst Theodore O'Neill.

This week, Bank of America/Merrill Lynch upped A123 Systems to a buy, though shares remain down for the past five trading days. However, if some analysts are getting more constructive on A123 Systems given the fact that the stock has declined by 38% this year, A123 Systems' own CEO has recently been selling shares. The recent sales, made on April 12 and May 16, were at share prices of $5.32 and $5.83. Granted, the A123 Systems CEO David Vieau only sold 2.2% of his shares for a value of $123,000, and the A123 Systems CEO still has a huge stake in the company. Additionally, the sales were made under the executive's 10b5-1 plan, the Securities and Exchange Commission rule that allows executives to design insider trading plans for financial portfolio planning and investment diversification purposes.

Still, some insider sales watchdogs say the SEC rule merely provides cover for executives to sell shares without having to admit they are making a call on the company's stock value. Additionally, Wunderlich's O'Neill wonders how the A123 Systems CEO could have been selling right after completing a secondary that valued the company's shares at $6, higher than either of his recent share sale transactions. The 10b5 plan allows the A123 Systems CEO to sell, but the Wunderlich analyst says that the CEO would not have been precluded from stopping the SEC rule from kicking into action if he had wanted to, and given the secondary going off at $6 at the end of March.

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