As you can see in the graphic below, for the most part US equities mirror those of the rest of the world. Well, at least we can say they tend to both move up and down together. There are times when one of the two considerably outperforms the other. The first instance of this performance divergence occurred beginning in 1986 when global equities turned tail and left US stocks in the dust. It took about a decade before they came back into balance.
For the next 20+ years the two pairs tracked fairly well except just before the 2007-’08 huge market draw-down where foreign stocks, once again, vaulted to the upside. In both cases of foreign stock out-performance, you needn’t look any further than the dollar for an explanation as it fell precipitously, bringing rise to foreign asset values.