Fannie Mae and Freddie Mac single-family mortgage servicing grew at a relatively stable pace during the fourth quarter of 2016, but the nonbank share was up significantly. A new Inside The GSEs analysis and ranking shows that the two guaranteed $4.496 trillion of single-family mortgage-backed securities outstanding at the end of December. That was up 1.0 percent from the third quarter and 0.8 percent higher than at the end of 2015. But nonbanks held the mortgage-servicing rights on some $1.476 trillion of GSE single-family MBS, up 4.7 percent from the end of the third quarter. Their GSE servicing grew a whopping 18.5 percent during 2016, while banks and other depositories managed a small 0.6 percent increase.