The small share of the secondary mortgage market enjoyed by the Federal Home Loan Banks has gotten considerably smaller this year as banks and thrifts are finding less reason to sell to the government-sponsored enterprises in this year’s ARM-dominated mortgage market. According to numbers compiled by Inside MBS & ABS, the FHLBank share of the total GSE market in the first six months of 2004 sank to just 2.4 percent. That compared to 3.9 percent for…