Top 10 most-crowded stocks investors may want to avoid

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A key data point smart fund managers look at is how "crowded" a stock is in terms of institutional ownership. UBS just put together a list of the "top 10 crowded trades" to help investors on this metric.

Bank of America Merrill Lynch's Savita Subramanian has said it's more difficult for crowded stocks to move higher since everyone is already in the trade.

Moreover, when sentiment shifts there may be more downside risk as investors flee for the exits at once.

In a note to clients Tuesday, UBS' Shanle Wu's team aggregated all the positions from global active fund managers, using FactSet institutional ownership data. They then compared the weightings versus the "relevant equity index benchmark" to calculate the investor and active net weight percentages.

Here are the top 10 most crowded stocks, according to UBS.