A metric relevant for debt mutual funds, This represents the portion of the portfolio invested into debt issued by private companies and its credit quality depends on the financials of the company issuing it, it is not backed by the government of the country. It can range from AAA rated to C/D rated assets. 

Investors can use these metrics to find out strategies that match their investment needs the best. An investor that prefers bonds with the least credit risk would prefer funds with higher allocation to sovereign debt.