FMNAT dividend = 8.25%, but is less liquid
FMNAS dividend = 7.75%
FMCKJ dividend = 7.875%
https://www.fanniemae.com/sites/g/files/koqyhd191/files/migrated-files/resources/file/ir/pdf/stock-info/series_T_05152008.pdf
https://www.fanniemae.com/sites/g/files/koqyhd191/files/migrated-files/resources/file/ir/pdf/stock-info/series_s_12062007.pdf
https://www.freddiemac.com/investors/pdf/FtFPrefStock-oc.pdf