Fannie's minimum capital requirement is calculated as follows: 2.5% of on-balance-sheet assets and 0.45% of its MBS and other off-balance-sheet assets. In other words, for every $1 billion of on-balance-sheet assets, Fannie has to hold $25 million of capital, but only $4.5 million of capital if they are off balance sheet. Thus, what would happen if Fannie had to shift on balance sheet, say, a fourth of its off-balance-sheet assets (a totally arbitrary proportion, of course)? One-fourth of $1.42 trillion is $355 billion of assets. A move on balance sheet would mean upping the capital held against those assets to $8.9 billion from $1.6 billion. The actual amount could be higher, since OFHEO is asking Fannie Mae to hold 30% extra capital. In that case, the higher capital amount would be $11.5 billion rather than $8.9 billion.