Despite its GSE status, there is speculation that Fannie Mae could end up testing a major securities law that no private company has yet tested – the limits of the Sarbanes-Oxley Act. Sarbanes-Oxley was enacted in 2002 in order to improve corporate governance, financial disclosure and the practice of public accounting in the wake of major corporate scandals. Under the terms of the new law, the chief executive officer and the chief financial officer can…