I use the Bank Of America Merrill Lynch US High Yield Master II index to track US high yield bond prices. The BondId for this index is H0A0 on the Merrill Lynch Index web site. I like this index because it includes interest earned each day in the index value and correlates very well with open end high yield bond fund value. (Note:Closed-end bond funds tend to trade with a lot of emotional noise and do not track this index well.)
The index has appreciated 55.5% in the last 12 months. But what is most remarkable is the trend persistence. The last down day for the index was November 30. Since then, it has been up for 24 straight days. During this win streak, the index has appreciated from 664.164 to 690.892 or about 4%. I have previously posted on TFCIX which correlates closely with the H0A0 index and is also on a 24 day winning streak.