How Apple Inc. got swarmed by Philip Elmer-DeWitt @FortuneMagazine April 9, 2013, 1:14 PM EST E-mail Tweet Facebook Google Plus Linkedin Share icons Chart: mspooner FORTUNE — “Swarming,” writes Mal Spooner, a Canadian money manager and financial columnist, “is the term now applied to the crime where an unsuspecting innocent bystander is attacked by several culprits at once… Because swarming at street level involves violence, it is criminal. However in financial markets it is perfectly legal.” And that, he says, is what happened to Apple AAPL last fall when traders detected weakness in what had been Wall Street’s darling stock and started selling it short in large quantities. As evidence, Spooner offers the chart above that shows short interest in Apple growing from 8.1 million shares in April 2012 to 20.5 million shares today — a market value roughly equivalent, he points out, to the gross domestic product of Malta. “I’ve never claimed to be all that smart,” he writes with classic Canadian false modesty, “but I just can’t figure out how aggressively attacking a company’s share price, selling stock that the seller doesn’t even own, for the sole purpose of transferring the savings of innocent investors into one’s own coffers… is a noble thing. Isn’t it kind of like a bunch of thugs beating someone up and stealing his/her cellphone declaring it was the loner’s own fault for being vulnerable?” One way for shareholders to avoid being swarmed, he suggests, is to instruct their brokers to stop letting short sellers borrow their stock to use against them. That can be accomplished by moving shares from a margin account to a cash account — which is exactly what some members of Investor Village’s AAPL Sanity group have decided to do. “Everyone who can make this change to their account should do so,” writes a member who calls himself AnAAPLaDay. “Pass the word and make it go viral. Perhaps we can organize a flash mob and create a short squeeze!” Whether a handful of retail investors can make a material difference when 64% of Apple’s shares are held by institutions is not clear. But it probably feels better than just standing there and getting mugged.