BUZZ-Ballard Power Systems Inc: Upgraded to "buy"
** Fuel cell stack maker's U.S.-listed shares up 2 pct at $3.2; stock has halved since touching an 8-yr-high in March
** Analysts at Sidoti & Co upgrade stock to "buy" from "neutral", according to Theflyonthewall.com
** Wall Street is divided on the stock: Of the five brokerages covering the stock, two have a "buy" rating, one has a "strong buy" and two have a "hold" on the stock
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