Natural personal credit unions that will be supervised by the new office include the $48 billion Navy Federal Credit Union, the $25 billion State Employees' Credit Union, the $15 billion Pentagon Federal Credit Union and the $10.6 billion Boeing Employees Credit Union.

Matz said the $9.5 billion SchoolsFirst Federal Credit Union is close to joining the other four credit union giants above the $10 billion mark.

The move has been in the works for about two years, Matz said. The idea came out of a systemic risk working group that put together options to improve safety and soundness, which met with NCUA executives twice to make the final decision.

Matz told NAFCU attendees a disproportionately large amount of NCUA resources are currently being spent supervising small credit unions, while a conversely small amount of resources are used to supervise large credit unions.

Additionally, the three largest credit unions are each larger than the entire National Credit Union Share Insurance Fund, which has $11.6 billion in assets as of May 31. As a result, Matz said, if one of those credit unions "got into trouble, we couldn't afford to rescue it."

The new office is expected to be budget neutral, Matz said.

"We wanted to find a solution that would be both efficient and effective," she said. "We didn't want to add any additional resources or staff."

The reorganization was also prompted by the reduction in the number of corporate credit unions in the past few years, she said.

Affected credit unions won't likely see any changes to their current examination regimen until 2014, Matz said, because the NCUA will spend 2013 making the internal transition and training staff.

Director Scott Hunt, who has experience examining natural person credit unions, "brings so much" to the new office "because he has expertise on both sides" of retail and wholesale credit unions, Matz said.