SAN FRANCISCO (MarketWatch) -- Past Securities and Exchange Commission probes of Bernard Madoff were incompetent, according to a report issued Wednesday by SEC Inspector General David Kotz. In his report, Kotz said that three agency exams and two investigations failed to uncover Madoff's multibillion-dollar Ponzi scheme despite warning signs. The report, however, found no evidence of improper ties between the SEC and Madoff's firm.