Which type of ETF could incur roll yield loss?

A futures-based ETF gains exposure by holding futures contracts rather than the physical commodity or underlying asset. Because futures contracts expire, the ETF must periodically sell contracts nearing expiry and buy later-dated contracts. This process is called rolling. Roll yield loss can occur when the futures market is in contango, meaning later-dated contracts cost more than near-term contracts. The ETF sells the cheaper expiring contract and buys the more expensive replacement, reducing returns over time. Physical-based ETFs hold the underlying commodity directly and therefore avoid this specific futures roll problem. Equity-based ETFs hold shares, while index-based ETFs track securities or indexes. The roll yield issue is specifically associated with futures-based ETFs.