​With oil prices moving on and off record highs, two brothers — Sam and Sasha — sense an investment opportunity.

Sam, the optimist, looks for the upside. He invests $1,000 in a two-times leveraged bull ETF. This fund aims to double the daily return of a crude oil index.

Sasha thinks prices for Brent crude, a class of sweet light crude oil, will drop. He buys $1,000 in units of the related leveraged bear ETF, which seeks to deliver double the gains if the oil index drops.

The next day Brent crude moves up 10% to $110 a barrel. The crude oil index makes a similar jump. That means Sam’s bull ETF runs up to $1,200, while Sasha’s bear fund falls to $800.

Another day goes by and Brent crude settles back to $100 a barrel — a 9.1 percent drop. So does the oil index. To double that move, Sam’s bull fund sinks to $982. Sasha’s bear fund rises to $946.

The result: Brent crude is the same price it was two days ago. So is the crude oil index. Yet if either brother sold his ETF shares at this time, he would lose money even before fees and transaction costs.