Charles Schwab Corp. says it is prepared to undo any trades made on Sunday – at no charge – during a time when a computer glitch assigned incorrect ratings to about 10% of the 3,000 stocks in its proprietary ratings system, according to The Wall Street Journal.  Schwab spokeswoman Sarah Bulgatz said the error was not in calculation, but in a shift in letter designations that represent the "hold" and "sell" ratings, reportedly the first time such a problem has occurred.
 
An estimated 3,100 executed trades were involved in the week-end glitch, which was followed on Monday with an urgent Web site post and phone calls to clients who were affected by it. Bulgatz told The WSJ that Schwab will soon be implementing a new quality-assurance tool to safeguard against such mishaps in the future.