Reuters Graphics Reuters GraphicsAmong factors fueling the swings is a flood of options trades, many of them short-term in nature.
A surge in options trading tends to boost hedging by market makers – typically large banks or financial institutions that facilitate the trades and need to position in equity futures to reduce their risk from unexpected market moves.
Their furious buying and selling can heighten short-term swings in stocks, adding to broader volatility, market participants said.
LOW POSITIONINGMeanwhile, many so-called "real money" investors such as pension funds and mutual funds have cut their stock allocations to the bone after months of equity volatility, another factor fueling stock swings.
At the same time, under-positioned investors have recently tended to jump aboard stock rallies, further extending the moves, market participants said.