N E W Y O R K, Oct. 15 — ImClone Systems founder Sam Waksal pleaded guilty to securities and bank fraud charges Tuesday in the biotech company's insider trading scandal. Waksal's admission is the second guilty plea in the investigation of insider trading on ImClone stock that has also focused on friend and investor Martha Stewart. He entered a plea Tuesday to six counts, including securities fraud, bank fraud, conspiracy to obstruct justice, and perjury. The former ImClone CEO was arrested in June on charges of trying to sell his shares and tipping off friends and family members who...