Tesla Inc. (TSLA.O) agreed to acquire battery-technology company Maxwell Technologies Inc. for about US$218 million in stock, as Elon Musk’s electric-car maker adds expertise in energy storage and power delivery.

The purchase price of US$4.75 a share, announced by Maxwell in a statement on Monday, amounts to about a 55 per cent premium to the target’s closing price on Feb. 1.

The companies share a common goal, Maxwell Chief Executive Officer Franz Fink said in the statement. The deal will allow Maxwell shareholders “to participate in Tesla’s mission of accelerating the advent of sustainable transport and energy.”

Tesla shares wiped out their premarket gains and were down less than 1 per cent to US$311.90 in early trading after the announcement. Maxwell shares were halted on the news.