 The U.S.-listed shares of Ballard Power Systems Inc. BLDP, -5.29 lost 0.7 in premarket trading Wednesday, after the Canada-based fuel cell products company reported second-quarter results that missed expectations as gross margin that turned negative, and said it expects pressure on gross margin to continue for the rest of the year. Net losses widened to 55.8 million, or 19 cents a share, from 21.9 million, or 7 cents a share, in the year-ago period. 