The ongoing growth of New Residential Mortgage resulted in an increase in concentration among the top servicers of single-family Fannie Mae and Freddie Mac loans in the fourth quarter.New Residential, a real estate investment trust that invests in mortgage servicing rights and related assets, has rocketed up the ranks of GSE servicers. After picking up its seller-servicer approvals in the third quarter of 2016, the company had amassed a $229.57 billion MSR portfolio by the end of last year.The REIT so far hasn’t invested in Ginnie Mae servicing. Its Fannie/Freddie holdings grew by 13.5 percent during the fourth quarter, enough to vault over Bank of America to become the third-largest investor in GSE MSR. New Residential pays subservicers to handle loan administration duties.