2018 when FNMA reports 4th QTR/Annual results in FEB 18, with current structure (may change?) they will have zero capital buffer.
Based on expectations for similar earnings 4th QTR 2017:
2016 results Fannie Mae Reports Net Income of $12.3 Billion and Comprehensive Income of $11.7 Billion for 2016
Company Reports Net Income of $5.0 Billion and Comprehensive Income of $4.9 Billion for Fourth Quarter 2016
I am doubtful storm damage impact to FNMA earnings being anywhere close to $1B. Doubtful this "scare tactic" will influence any immediate action much less by next FEB when they report.