Reversing at least temporarily a long-running trend in the mortgage market, the four biggest banks in the U.S. expanded their presence in the GSE single-family market in the third quarter of 2016. Together, Wells Fargo, Chase, Bank of America and Citigroup delivered $61.88 billion of single-family loans into Fannie Mae and Freddie Mac mortgage-backed securities during the third quarter, according to a new Inside The GSEs analysis and ranking. That was up a hefty 45.0 percent from the second quarter, well above the 29.7 percent increase in overall MBS issuance by the two GSEs. The four megabanks, all with over $1 trillion in assets, expanded their combined GSE footprint by 2.2 percent from the second quarter.