For those of you who don't know, the SEC is a Wall Street watchdog that investigates compaines on the stock market who may be breaking the law. In this case they have requested information from Acclaim, Activision and THQ as part of what looks to be an industry-wide investigation. This doesn't mean the companies have done anything wrong just yet but major publishers and distributors getting in this kind of trouble wouldn't be a good thing. Here's a bit more from Gamespot:
Let's hope everyone has their books in order, an industry-wide shakedown wouldn't exactly be healthy.
The filing said that the investigation "appears to be focused on certain accounting practices common to the interactive entertainment industry, with specific emphasis on revenue recognition."