There are two different ways in which ETFs track an underlying index.

Performance may not even closely track the underlying index, particularly in volatile markets.

In theory, the funds are supposed to track closely the value of an underlying index.

How closely does the ETF track an underlying index?

A leveraged ETF uses financial derivatives and debt to amplify the returns of an underlying index.

In recent days, the gap between the ETF's price and the underlying index has widened amid more volatility.

Its underlying index structure is designed to quickly retrieve all occurrences of a tryptic peptide in UniProtKB records.

An exchange traded fund is a collection of securities such as stocks that are lumped together in an underlying index.

Inverse ETFs try to achieve the opposite performance, which allow investors to make money when the market or the underlying index declines.

A 5 percent increase in the underlying index would then net the investor $4.84 million.

The largest holding in the ETFs accounts for about 4 percent of the underlying index that the managers track, so it is well diversified.

If the underlying index had moved up 5 percent during that time, the investor would net $4.58 million.

Between January 27 and February 7, the fund lost 7.7 percent while the underlying index showed a gain of 2.1 percent.

Between Jan. 27 and Feb. 7, the fund lost 7.7 percent while the underlying index showed a gain of 2.1 percent.

China CSI300 stock index futures for September rose 0.3 percent, to 3,731.6, 23.71 points below the current value of the underlying index.

China CSI300 stock index futures for August fell 1.2 percent, to 3,674.8, 18.82 points below the current value of the underlying index.