Traders are making a big change to how they use the world's hottest investment product

Some investors use exchange-traded funds to achieve easy portfolio diversification. Others are attracted to their relatively low fees.

But what they're not doing is using ETFs to bet on share declines. At least not lately.

Short interest currently sits at 6.1% of total ETF assets, the lowest level since the financial crisis, according to data compiled by JPMorgan. That comes amid a roughly 30% drop in total short interest for US-listed funds over the past seven months.

The measure now sits at $135 billion, down from a post-crisis high of $194 billion reached in September 2015, the data show.

Still, this doesn't necessarily mean investors are giving up on stock market shorts altogether - they just prefer making wagers on individual names. Single-stock short interest, measured across all S&P 1500 constituents, is currently in the middle of its range since the start of the eight-year bull market.

"It does not appear as though shorts have departed from the market," the quantitative and derivatives strategy team at JPMorgan wrote in a client note. Investors preferences have simply shifted away from ETFs and towards single stocks, they said.

One possible explanation for the move away from ETF shorting is that active management firms are making a conscious efforts to separate themselves from the indexes normally tracked by such funds, according to Bank of America Merrill Lynch. This might be due to mounting pressure from consultants to shift away from benchmarks, a development that's pushed single stock exposure to a record high, the firm said.

The dynamic of stocks trading on independent fundamentals, rather than having performance dictated by their presence in ETFs, can also be seen in a measure known as implied correlation.

The CBOE S&P 500 Implied Correlation Index, a gauge of lockstep moves in the S&P 500, is fresh off its lows for the year, according to data from Bloomberg. The index has dropped 13% so far in 2017 as investors have studied first-quarter earnings reports and delineated between the winners and losers of President Donald Trump's expected policies.

Regardless, ETFs aren't going anywhere. As of February, passive investments like ETFs and index funds accounted for 28.5% of assets under management in the US. That share will rise to more than 50% by 2024 at the latest, according to a Moody's forecast.