WASHINGTON -- The Treasury Department is putting the finishing touches to a plan designed to shore up Fannie Mae and Freddie Mac, according to people familiar with the matter, a move that would essentially result in a government takeover of the mortgage giants.

The plan is expected to involve putting the two companies into the conservatorship of their regulator, the Federal Housing Finance Agency, said several people familiar with the matter. That would mean the government would take the reins of the companies, at least temporarily.

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