Traditional futures expire, forcing funds to sell near term contracts and buy later ones in a costly process known as the roll. Perpetual futures never expire, which could remove that step and concentrate trading in a single, continuously traded contract. Regulators have taken notice, with the CFTC approving a perpetual contract on Bitcoin at a US exchange earlier this year. For ETFs, the appeal is cleaner exposure and potentially deeper liquidity for market makers, with leveraged, volatility and managed futures products among the likeliest candidates. The catch is that rolling costs are replaced by funding payments, where one side pays the other and rates can swing, so the cost of holding exposure does not simply vanish. Some markets, such as oil, may benefit little, and simple spot ETFs may not need the technology at all. Perpetuals change the economics rather than erase them. 

Finsum: A product with no expiration date still has a price, so investors should ask what replaces the cost they no longer see before deciding whether perpetual futures belong in a portfolio.