The FRED series Mortgages - Assets - Balance Sheet of Nonfarm Nonfinancial Corporate Business is now known as Nonfinancial Corporate Business; Total Mortgages; Asset.
The source series id is FL103065003.Q.
This series appears in Table B.103. For further information see the assistance provided in the guide to the Financial Accounts at http://www.federalreserve.gov/apps/fof/.
Board of Governors of the Federal Reserve System (US), Nonfinancial Corporate Business; Total Mortgages; Asset, Level [MABSNNCB], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/MABSNNCB, March 19, 2019.