An exchange-traded fund named for Texas oilman T. Boone Pickens will swap its strategy, embracing renewable energy stocks in a sign of the times for fossil fuels. But while renewables may seem more cutting-edge than oil, that doesn’t necessarily mean investors should automatically gravitate to the new venture.

The ETF, the NYSE Pickens Oil Response Fund, or BOON US:BOON , will become RENW, the Pickens Morningstar Renewable Energy Response Fund, in mid-August, embracing a strategy that “seeks to identify companies that are leaders in the transition to a low-carbon economy,” fund managers said in a filing.

Pickens indirectly controls TriLine Index Solutions LLC, which is the fund’s investment adviser.

A change like this isn’t as rare as you might think, said Ben Johnson, director of global ETF research at Morningstar. Sometimes they’re “ho-hum,” swapping out a well-known index like the S&P 500 SPX, +1.59% for a proprietary index of mostly the same large, liquid, publicly-traded stocks, Johnson said.

But sometimes a swap is a lot more disruptive, like in late 2017, when a Latin America real estate ETF suddenly decided to invest in marijuana instead. For some investors, an “about-face” like the one adopted by BOON’s investment advisers might be just as jarring, Johnson noted.

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Unfortunately, investors have little say in it, he told MarketWatch, not unlike when an actively-managed mutual fund or ETF swaps managers and the new staff brings fresh ideas.

“This is just one example among many where it’s clearly a failed first attempt and an attempt to pivot and bring to market something more successful,” Johnson said. BOON has lost about 23% over the past 12 months, a period when major broad stock indexes DJIA, +1.33% are up about 3-4%, but it has rallied since the start of 2019, returning a little over 7%.

This transition at least offers investors options. If the fund shut down altogether, it would likely leave investors with a pile of cash and unexpected tax bills, Johnson noted. That happens more often than you might expect — the ETF “mortality” rate is close to 30%, he said.

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As for the new venture, RENW, Johnson advises some soul-searching for anyone interested in the approach. “There have been a number of niche funds launched within that space, all with varying degrees of success, some generally unsuccessful,” he said.

(It is important to note that despite Pickens’s reputation as a “Texas oilman,” he has previously made professional bets, some big, on renewables. In 2008 he launched a policy proposal known as the Pickens Plan to build wind farms that would capitalize on natural gas, in an effort to achieve “American energy independence.”)

As of 2018, according to the U.S. Energy Information Administration, 11% of all U.S. energy use was renewables, a statistic that could signal some upside growth potential. Still, Johnson points out that in many smaller industry segments “there are few pure-play public firms” — those engaged primarily in the specific area investors are trying to reach.

And the analysis shouldn’t end there. “It’s important to understand that you’re making, a very complicated multi-part bet with these niche firms. Part of the bet is, is this theme legitimate? Is it durable? The second part is,can this fund provide me high fidelity exposure to firms that derive the majority of their revenues from this theme?”

And even if those two boxes get checked, there’s a final step, Johnson said. As with any stock or other asset, valuations may be the most important component. “Even if you get the first two, if you’re not buying at the right price, it’s probably not worth it.”

BOON will become RENW on Aug. 14, with an expense ratio of 65 basis points, a bit lower than the existing fund’s fee.

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