The US Corporate Investment Grade credit risk premium has been analyzed from January 1973 to April 2018. The average excess return of US corporate IG bonds over US Treasuries was 60 bps per year, which is considered low. Instead of analyzing this credit excess return alone, a portfolio perspective was proposed, considering corporate bonds as packages offering exposure to interest rate and credit risks. The total risk premium on corporate bonds is a combination of a pure asset risk premium and a factor risk premium. The implied credit risk premium was found to be 44 bps, lower than the historical average credit excess return of 60 bps.