An unprecedented effort to create funds that would have delivered four times the return of the S&P 500 has run into a regulatory roadblock.

The Securities and Exchange Commission earlier this month approved an application from ForceShares that would have created the two exchange-traded offerings — the ForceShares Daily 4X US Market Futures Long Fund and ForceShares Daily 4X US Market Futures Short Fund.

The funds would use derivatives to represent four times the gains or losses of the futures contract, and the respective tickers were to be UP and DOWN.

However, some market participants complained that the funds were risky and could cause unwitting buyers to sustain major losses.

In an unusual move, the SEC commissioners are reviewing the approval that came from staff members and could shoot down the funds, according to a report in The Wall Street Journal. The three-member commission also could uphold the decision, though the move to review the staff approval could signal trouble for the funds.