The FRED series Treasury Securities - Assets - Balance Sheet of Nonfarm Nonfinancial Corporate Business is now known as Nonfinancial Corporate Business; Treasury Securities; Asset.
The source series id is FL103061103.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; Treasury Securities; Asset, Level [TSABSNNCB], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/TSABSNNCB, April 20, 2018.