Just as the rise in U.S. stocks is showing signs of stalling, statistics show that trading in ultra-short-term options has soared to a record high. With derivatives becoming more and more a tool for short-term gaming, some institutions are concerned that a new round of volatility risk may be brewing in the face of risk factors such as a downgrade of the U.S. credit rating and the specter of a recession, which could set the stage for a sell-off in the coming days and weeks.