November 5th is Bank Transfer Day, and its timing is no accident. Kristen Christian, the person who thought up the idea, chose the date that was once popular in Britain as Guy Fawkes Day.

But Bank Transfer Day proponents aren't the only ones who might act on Nov. 5. The hacker group Anonymous has adopted the date in recent years as a favored day of action. The group's already made one dramatic proclamation, and there could be other threats lurking. Everyone is hopeful that Bank Transfer Day goes off without a hitch, but a few bad eggs might make this Saturday a day that one company would rather forget.

Remember, remember the fifth of November
Anonymous and Guy Fawkes are an unlikely pairing. Those who've seen V for Vendetta know the background, but for anyone who's never seen the movie, here's the short version of the story behind Guy Fawkes: An affected English anarchist in anonymous attire attempts to adjourn the administration through means most abominable, assembling ample explosives adjacent to Parliament while also assassinating assorted authorities. Also, Natalie Portman shaves her head.

The film's signature prop is a Guy Fawkes mask, and this in combination with the message of rebellion gave the "hacktivists" a stylistic mode of expression. The mask has been showing up occasionally at Occupy rallies, and a version of the mask has also been featured on the Bank Transfer Day's Facebook page.

The gunpowder treason and plot 
As Fool contributor Morgan Housel pointed out in his review of the day's possibilities, Bank of America (NYSE: BAC) and Citigroup (NYSE: C) might not mind the action. However, credit unions have already been inundated with new accounts, as a report from the Credit Union National Association shows that 650,000 new members have joined credit unions since Sept. 29. This might not seem like a staggering number, but the month's surge outpaced credit union membership growth for all of 2010. By that measure, Bank Transfer Day is already largely superfluous, since the number of listed attendees is barely more than a tenth the number of accounts recently opened.

I know of no reason why gunpowder, treason ...
One company that's been a persistent critic of the movement might see harsher action on Nov. 5. Anonymous has declared war on Fox News, a division of News Corp. (Nasdaq: NWS) (Nasdaq: NWSA), threatening to make an example of the broadcaster's website. Fox News has been a minor target in Anonymous' crosshairs before, but that was a small fusillade compared to the barrage that some expect this time.

Sony (NYSE: SNE) knows all too well the pain a hacker collective can cause. Multiple attacks were launched against its PlayStation Network, as well as several of its websites. The attacks began in April but show no sign of ending, with another attack just last month. The stock has lost at least 35% since the beginning of the assault, and the company's woeful financial situation doesn't help matters in the least.

... Should ever be forgot
Strangely, two companies might earn little windfalls from all this masked bombast. Time Warner (NYSE: TWX), the parent company of V for Vendetta distributor Warner Brothers, owns the rights to the likeness and receives royalties with every sale. The mask is a top seller on Amazon (Nasdaq: AMZN), with several different versions showing up on their best-seller list. While I'm not aware of Anonymous ever having called for the wholesale destruction of capitalism, its anarchic stylings make this not without its small ironies.

Even if the big banks don't go down on the fifth of November, they face plenty of other threats. They tried to get customers to switch to credit cards, but those might soon be worthless. Find out more about the technology threatening to sap bank profits in this new video report. There are no hidden fees here; it's a free Motley Fool exclusive, and it won't be available for long.