UBS: Here are the 9 most crowded stocks

In a stock market increasingly ruled by machines, it's still important to know what the humans are doing.

After all, they're the ones still investing based on such factors as fundamentals and valuations, while their price-insensitive computerized counterparts operate off highly-tuned algorithms.

And following the herd can really pay off when the market is flourishing. The more people that pile into a stock during an up-market, the further its share price will climb.

It's a momentum-driven strategy that looks simple on the surface, but can backfire in spectacular fashion at the first sign of turbulence. The more crowded a trade, the more painful the fall as investors rush to the exit simultaneously, spurring a vicious unwind.

With all of that considered, UBS has compiled a list of the nine stocks most crowded with active managers. In order to do so, the firm created an active trading portfolio, calculating weights for each company. It then compared those to benchmark index weightings, and ranked the stocks with the highest excess active share.

Here's a list of the nine stocks identified by UBS as of June 23, arranged in descending order of global active weighting: