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April 2 (Reuters) - Plug Power Inc said it bought fuel-cell stack maker ReliOn Inc for about $4 million in an all-stock deal, as the company looks to diversify its supplier base.
Plug Power shares rose 4.5 percent after the bell as the deal also helps the fuel-cell maker expand into the stationary back-up fuel cell market.
Canada's Ballard Power Systems Inc is currently Plug Power's exclusive supplier of fuel-cell stacks in North America and some European countries. The stacks convert hydrogen and oxygen into electricity.
The U.S.-listed shares of Ballard Power were down 3 percent in extended trading. They closed 8.5 percent higher at $4.87 on the Nasdaq on Wednesday.
Plug Power said it expects the acquisition to add to earnings in 2015 and contribute to the development of its GenDrive fuel-cell systems.
Spokane, Washington-based ReliOn's customers include AT&T Inc, Sprint Corp and Verizon Communications Inc .
Shares of Plug Power, which expects to post its first-ever profit in the fourth quarter this year, closed at $7.48 on the Nasdaq. They have sky-rocketed 4,335 percent in the past year. (Reporting by Shubhankar Chakravorty and Sneha Banerjee in Bangalore; Editing by Sriraj Kalluvila)