Penn has served as a key strategic advisor to Bill Gates and Microsoft since the mid-1990s. Penn began working with Microsoft when the company faced antitrust litigation initiated by the U.S. Department of Justice. Penn also created the famous "blue sweater" advertisement that featured Bill Gates, which were intended to restore trust in the company amid the antritrust litigation. In 2006, a survey of global opinion leaders found that Microsoft was the world's most trusted company, an accomplishment which "The Wall Street Journal" partially attributed to Penn's advice.