By Nate Raymond NEW YORK (Reuters) - A U.S. judge on Tuesday dismissed two securities fraud counts against Rengan Rajaratnam, the younger brother of Galleon Group founder Raj Rajaratnam, in a surprise development in the federal criminal insider trading case. Rengan Rajaratnam, a former Galleon fund manager, still faces a conspiracy count, after U.S. District Judge Naomi Reice Buchwald at a hearing in Manhattan dismissed other counts related to improper trading in technology company Clearwire Corp. Buchwald said the question was whether Rengan Rajaratnam traded on inside information about Clearwire knowing the tipper breached his duties to keep it secret and in exchange for a personal benefit. "I find a reasonable jury could not so find," she said. The decision, which is not appealable, spared Rajaratnam from the most serious charges he faced.