"The space has tended to move as a whole," Adam Krop, an analyst with New York-based Ardour Capital Partners said, in an interview. Several solar energy companies were riding the coattails of LDK and SunPower, he said. Shanghai, China-based JA Solar Holdings Co. increased 4 percent to $7.41 while Suntech Power Holdings Co., a Jiangsu, China-based solar cell maker, was also 4 percent higher. "The space has been really undervalued for the past four to six weeks," Krop said. "With all these positive news announcements, eventually there has to be some positive movement." Trina Solar Ltd. of Changzhou, China, increased 2 percent to $25.53. First Solar Inc., the biggest U.S. solar company, advanced 2 percent as well to $136.20. Apollo Solar Energy Technology Holdings Ltd. of Hong Kong rose 1.8 percent. LDK Solar is not part of the WilderHill index.