It’s boom time for short and leveraged exchange-traded funds, with many in the sector winning assets, but as regulators take a closer look at what is being offered, there could be stormy times ahead – and some may not survive.

These ETFs, which either let people magnify bets or take bets against markets, enjoyed a bumper year in 2015. Assets in the products globally climbed 14.1% to $67.9 billion by the end of December from $59.5 billion a year earlier, according to Boost, a specialist short and leveraged fund provider owned by ETF issuer WisdomTree.