Top Oil ETF Accused of Risk-Disclosure Flaw Amid Market Rout

The world’s largest exchange-traded fund linked to oil has been hit with at least one class action lawsuit after a plunge in prices led to billions of dollars in losses and allegations that investors weren’t properly warned of the risks.

The lawsuit, filed in the Southern District Court of New York, alleges that the United States Oil Fund LP, known by its ticker USO, stated it would achieve its objective by investing assets into the prompt West Texas Intermediate futures contract without fully disclosing the risks to investors. Even as the market was roiled by a price war and ...