Fannie Mae ( FNM) said Thursday that former CEO Daniel Mudd will resign from the board of directors immediately. Fannie did not provide a reason for Mudd's departure. The move comes just weeks after the government placed Fannie and its sister company, Freddie Mac ( FRE) into conservatorship and replaced top executives. The mortgage-finance giants had been on the brink of collapse, with plunging share prices and weak capital levels. In after-hours trading on Friday, Fannie shares were up 2.6% at $1.60, and Freddie was down 1.7% at $1.77.