Note how HYG is just sliding slower at a steady pace. Clearly, investors piling into the USDollar are NOT buying High Yield Corporates, but if they are, it means that existing investors are swamping them with more supply than they can handle. In either case, this is a warning sign to pay attention to.
When this "log rolls over", there could be some fireworks.
I'll put "buy on HYG" and "sell on SPY" here.