WASHINGTON (Reuters) - Housing giants Fannie Mae and Freddie Mac would have to raise over $200 billion in new capital to fall in line with a rule finalized on Wednesday by their regulator. The new rule from the Federal Housing Finance Agency places bank-like capital requirements on the pair, and was seen as a key step in preparing the two to eventually leave government control and return to operating as private companies. The rule is “substantively similar” to one proposed by the FHFA back in May, the agency said. It establishes new capital and leverage requirements for the pair, as well as buffers that would allow the enterprises to continue guaranteeing mortgages even in an economic downturn. Fannie and Freddie guarantee roughly half of all the nation’s mortgages. All told, the final rule anticipates the pair would need roughly $283 billion in total capital. That is up by about $40 billion from the proposal, due in part to growing portfolios at Fannie and Freddie and also due to a ramped-up requirement for how much risk-based capital they should hold.