Volatility-linked exchange traded funds that follow VIX futures such as ProShares VIX Short-Term Futures ETF (NYSEArca: VIXY) have shown signs of life recently on rising trading volume following the steady descent from October.

A leveraged exchange traded note, VelocityShares Daily 2X VIX Short Term ETN (NYSEArca: TVIX), has seen volume spike in a volatile week.

These volatility-linked products rise when investors are seeking protection in options markets from stock pullbacks. However, it’s critical to remember they track VIX futures contracts, rather than the spot price.

The CBOE Volatility Index, or VIX, is a widely monitored indicator for implied future volatility.

Volatility ETFs can be used by traders to hedge portfolios or speculate on market weakness.