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In Stock Picking, It's Man Versus Machine

There was a time investors loved inefficiencies.

How's this for an inefficiency: According to data provided by Cleve Rueckert of Birinyi & Associates, 78 percent of the S&P 500 is currently moving with the market.

That's right—almost everybody is doing the same thing, thanks to computers, ETFs, flash trading and everything else that has made real investing, certainly the Peter Lynch style, seem like a joke.

It wasn't always this way. Back in April the correlation was more like 50 percent. And if you go back further to the good old days of the mid-90s, according to Rueckert, it was around 30 percent.

Those were the days when good, old-fashioned stock-picking still meant something—when inefficiencies meant betting against a group of investors who disagreed on the fundamentals of a company.

The trouble this time is that betting against this inefficiency, using classic fundamental research, can be meaningless when stocks move largely based on nothing having to do with underlying fundamentals.

As we focus on Man vs. Machines, one big question all investors should be asking: If the market has become its own self-fulfilling prophecy, can this possibly have a happy ending?

Or is an “event” in the offing? Nobody can say for sure, but my guess is that the “fat finger” fiasco from May was simply a tap on the shoulder.

Onward.

More from Herb Greenberg:

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