Here is the reason for the surge: all day everyone sold off yen and bought whatever risk assets they could find. The carry trade is back. Risk on. As equities surged higher, all the new found money had to be put somewhere: just as equity indices stormed higher so HY rushed back to the day's highs. Stocks, bonds, who cares - buy it all.
In the meantime credit is once again scratching its head at the lemmingness of stocks. Even with Goldman stock rising by $2.50, its CDS was 7 bps... wider! Nothing makes sense anymore. Sell yen, but whatever crap you can still get your hands on. The crappier the better. Obama said so.