A former private wealth adviser for a unit of Lehman Brothers Holdings Inc can keep a lucrative signing bonus he received from the firm three years before it collapsed, a securities arbitration panel has ruled, Reuters reported yesterday. Lehman lost its bid to recoup $1.8 million from William Gourd, who joined the firm in early 2005, according to a ruling this week by a Financial Industry Regulatory Authority arbitration panel. Lehman Brothers Holdings Inc. has been pursuing roughly 50 of its former licensed securities professionals to return portions of the bonuses they received when hired.