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, run by its successor, citigroup and now by ftse russell. the big is generally used for managing broad debt portfolios from short to long-dated maturities, similar to the barclays capital aggregate bond index ("agg") or the merrill lynch domestic master.