High Yield Index Yield

High yield spreads are still slightly wider than they were at this time last year, but since treasury rates have fallen, the effective yield is back to multi-decade (perhaps all time?) lows on the BofA High Yield Master Index.  At 14x earnings, the earnings yield of the S&P 500 is roughly the same as the effective yield of the high yield index.  Is one of these metrics poised to break lower?  

Given that there is a material risk of default for high yield bonds, it would seem that there should be some base level of interest rate received that compensates for the credit risk...if that level is 7.5% then there's not much return to capture from high yield other than carry interest.