(Adds Arotech comment, updates shares)
April 22 Shares of Arotech Corp, a maker of lithium batteries for military tanks, fell as much as 17.5 percent after a report on stock commentary website Seeking Alpha said its shares were not worth more that $2, less than half of Monday's closing price.
Arotech's shares more than doubled between Feb. 26 - when Tesla Motors Inc said it planned to raise $1.6 billion to finance a new battery factory - and April 1, when the company said it would not enter the electric vehicle market.
A writer identifying himself as Small Cap Machine said on Seeking Alpha that Arotech shares were "massively overvalued" considering the fact it would not benefit from the Tesla factory and that there was small potential for a big military contract.
The author described himself as a hedge fund manager with a short position on Arotech shares. (r.reuters.com/pyv68v)
An Arotech spokesman declined to comment.
The stock was down about 15 percent at $3.78 in early afternoon trading on the Nasdaq. (Reporting by Sagarika Jaisinghani in Bangalore; Editing by Don Sebastian)