Kosta Kartsotis, chairman and chief executive officer of Fossil Group, reduced his share of the company’s stock by 36 percent over the past two months. InsiderInsights, which tracks stock transactions by company insiders, labeled Mr. Kartsotis’ recent sales as “significant.” Fossil’s CEO, who has not received a salary or stock awards since 2004, currently owns 7.8 percent of its outstanding shares.