Playing follow the leader doesn't usually work when it comes to investing. However, in many ways 2017 has been different, featuring record highs in stocks, record low volatility and an ever changing political landscape. "Over the last several years, buying the most underweight stocks and selling the most overweight stocks has consistently generated alpha, although performance in 2017 so far has bucked the trend," Bank of America said in a recent research note. 

Since 2014, buying the ten most underweight stocks and selling the ten most overweight has been a lucrative strategy for investors. By selling the overweight stocks and you are avoiding the market's herd mentality. Billionaire investor and philanthropist Warren Buffett once said, "be fearful when others are greedy and greedy when others are fearful." Translation: be careful buying something that everyone else is buying. (See also: Copying Buffett Will Lead This Stock to Outperform.)

However, 2017 has been a year to put aside your fear and find out what your neighbor is doing because crowded trades have been the winners, and there is one reason, and one reason only for this: tech stocks. (See also: Tech Stocks May Still Have Plenty of Room to Run.)

FAANG You Very Much

Investors have a lot to be thankful for in 2017, but nothing more so than the tech sector. Whether it's FANG or FAANG doesn't matter. For those investors who have been riding the tech acronym – and there's been plenty of them – it's been a bumper first half. According to Bank of America, large cap active managers set another record, and are now 25 percent overweight tech relative to the benchmark, and despite this, returns keep growing, making 2017 a year to follow the leader. 

In addition to those betting on tech stocks, the number of people betting against tech stocks continues to plummet. "Short interest on FANG/FAAANG stocks has come down to near record low levels of 0.9% of float over the past year," Bank of America said.

It's not just the tech sector where investors are giving up. Short interest across the board is down as bears continue to lick their wounds. According to data from S3 Partners, the number of people betting against the SPDR ETF (SPY), which tracks the S&P 500 has reached a four-year low.