[nickles]

> It's a concept that fits nicely in the category of technical analysis, but not one that allows you to find any particular market insights.

It's useful for hedging risk

> The only broadly meaningful concept you can get out of anti correlation with the market would be bonds because interest rates increasing push down the estimated future cash flows of publicly traded companies, affecting their valuations.

This is wrong. Consider pair trading or long/short strategies, both of which rely on estimating correlations.