bitcoins huge drop explained! naked shorting??? maybe

exchanges adding margins and shorting are going to cause huge drops and huge rises in low circulation coins just like stocks because most people don't understand how dangerous margins and shoring can be and I wonder if naked shorting has started in exchanges since they can control prices if u look at yesterdays drop and arbitrage was huge $400 between some exchanges why naked shorting only explanation to me naked shorting is when an exchange will sell u bitcoin that they don't own and force a drop in price once u want to withdraw to cover the short now I originally thought it was hard to do because of he block chain but when ur coin is with a exchange its not in ur wallet its in there's and they can manipulate as long as they have enough and only force a huge drop in price when a sell out starts and that's exactly what happen people started selling and it dropped 300 in minutes and then another 500 when people started withdrawing to cover there shorts opinions plz