The transfer of a major branch of industry or commerce from private to state ownership or control. Takings Clause A property owner may bring a claim in federal court under the Fifth Amendment when the government has violated the Takings Clause by taking property without just compensation.
When the FHFA with the Treasury took over Fannie and Freddie the Treasury received 79.9% warrants with an option to convert the warrants to common stock. If and when the Treasury converts the warrants to common stock any amount above the 79.9% is considered a takeover of the companies de facto Nationalization. The amount of debt the companies held at the time of the takeover if added to the National Debt this amount would have pushed passed the threshold of the limit of the debt ceiling: This is the reason for the limited amount of 79.9%.
The Congressional Budget Office (CBO) considers the conservatorship as Unfunded Liabilities, this is liabilities not added to the national debt but debt the U.S. States Government has said we will pay. The National Debt today stands at $31 trillion. The US Unfunded Liabilities are $172 trillion. So, in one sense the U.S. States Government has already Nationalized Fannie Mae and Freddie Mac. See link below...
Note: upper left hand corner US National Debt and bottom right US Unfunded Liabilities.
Yes not only was the 10% dividend designed to keep them under, write down of DTAs also had a impact. HERA (or it's misinterpretation) allowed conservator to take decisions that were contrary to 'Conservation' without judicial review.