Score another round this week for Frank Quattrone. Silicon Valley's once-powerful investment banker won a ruling Friday that overturned a order banning him for life from working in the stock-market industry. The Securities and Exchange Commission voted 5-0 to overturn the ban imposed by an industry regulator, the National Association of Securities Dealers. Now NASD must decide whether to try again to discipline Quattrone for refusing to testify in an investigation of activities during the technology industry boom. Earlier this week, on Monday, a federal appeals court in New York overturned Quattrone's conviction on charges of obstructing justice. Prosecutors have...