The Semi's have led the broad market ever since 2012. That is not the be-all, end-all but it is notable. The market has other leaders now, like the speculative momentum going on in Internets and Biotechs along with whatever reason the banks are still going up despite suspect interest rates (this bears watching because one of these things is off sides; either banks or yields).

Anyway, SOX-SPX over shot to the upside thrice previously so I suppose it can do so to the downside as well before regaining the channel. But as of this moment, the ratio is breaking down.