Although mortgage bankers are enjoying their strongest profit margins in years, smaller nonbank shops continue to live in fear that Fannie Mae and Freddie Mac under the auspices of their regulator may soon unveil higher net-worth minimums. Officially, the net-worth minimum is set at $2.5 million for both government-sponsored enterprises, although Fannie Mae has imposed volume limits on some newly approved seller/servicers that have posted big increases in their sales to the GSE. Several industry executives and their outside advisors fully expect...