The outcome of the securities fraud case leveled against six former top executives of Fannie Mae and Freddie Mac could hinge on what exactly is considered a subprime loan. At least one defendant is prepared to argue that there is no standard definition.In fact, the GSEs appear to still be reporting their subprime and Alt A exposure in much the same way they did in the period covered by the Securities and Exchange Commission lawsuits.Late last week, the SEC pulled the trigger on its three-year investigation of claims that the two GSEs failed to disclose to investors the companies’ exposure to subprime mortgages prior to the 2008 housing market crash.