The Salomon Broad Investment Grade Index (known as the Salomon BIG or Citigroup BIG) is a common American Bond index, akin to the S&P 500 for stocks, originally owned by Salomon Brothers and now run by its successor, Citigroup. The BIG is generally used for managing broad debt portfolios from short to long-dated maturities, similar to the Lehman Aggregate ("Agg") or the Merrill Lynch Domestic Master.
The BIG includes treasuries, agency debt, corporates, non-corporate credit, mortgage-backed securities, and asset-backed securities (ABS). Unlike the Agg, it includes 144As, but unlike the Agg, it does not include municipals or commercial mortgage-backed securities (CMBS). Like the Agg, the BIG does not include any inflation linked bonds, and is limited to investment grade securities, including no high-yield debt or emerging market debt.