Answer
Yes, Anderson Silva has lost a fight due to disqualification. He was disqualified for throwing an illegal knee to the head of his opponent, Chris Weidman, during their middleweight title fight at UFC 168 on December 28, 2013. The knee landed flush on Weidman's head and caused him to stagger backward and fall to the canvas. The referee immediately stopped the fight and awarded the victory to Weidman.