Section 929U of Dodd-Frank amended the Securities Exchange Act of 1934 to add that in enforcement investigations, 

Not later than 180 days after the date on which Commission staff provide a written Wells notification to any person, the Commission staff shall either file an action against such person or provide notice to the Director of the Division of Enforcement of its intent to not file an action. 

Section 929U further provides that in certain "complex actions," the Director of the Division of Enforcement has the power to extend this deadline for an additional 180-day period, up to two times.

A potential SEC case against Daniel Mudd, the former CEO of Fannie Mae, may be the first to come to a head under the new 180-day deadline.  Bloomberg reports that on March 11, 2011, the SEC made a Wells call to Mudd. In a Wells call, the SEC's enforcement division advises a person or entity that it will recommend that the Commission authorize an enforcement action against that person/entity. The March Wells call thus triggered the new 180-day period provided in Section 929U, and was set to expire on Tuesday of this week. It is unclear at this time whether the SEC filed a case, decided not to file a case, or obtained an extension.

Bloomberg points out that one potentially unintended consequence of Section 929U is that the SEC may begin to delay issuing Wells notices. The article states that "some SEC lawyers have been postponing sending the notices to avoid starting the 180-day clock."