The U.S. Securities and Exchange Commission (SEC) has sent a series of warning letters to some of the country’s most prolific issuers of high-leverage exchange-traded funds (ETFs), effectively blocking the rollout of products designed to deliver two- or three-times the daily returns of equities and commodities.

In nine letters released Tuesday -- nearly identical in content—the SEC notified firms including Direxion, ProShares and Tidal that it will not move forward with reviewing their proposed leveraged ETF offerings until key regulatory concerns are addressed.

At the center of the SEC’s objections is the risk profile of these products. The regulator warned that the exposure embedded in the proposed funds could exceed the agency’s limits on how much risk a fund may assume relative to its assets. Leveraged ETFs typically use derivatives to amplify daily performance, which can generate significant volatility and magnify losses, especially in turbulent markets.

The letters instructed fund managers to either revise their investment strategies to comply with the SEC’s risk framework or formally withdraw their applications. Until then, the proposed high-leverage ETFs will remain on hold.

The move underscores the SEC’s increasingly cautious stance toward complex retail investment products at a time when demand for higher-octane trading strategies continues to grow.