Exchange traded funds (ETFs) and products designed to profit from rising market volatility have fallen back close to their February low after a brief spike.

The iPath S&P 500 VIX Short-Term Futures ETN (NYSEArca: VXX) is by far the largest in the group with a market cap of about $1.4 billion. [Fueled By Pessimistic News, Volatility ETFs and ETNs Surge.]

The exchange-traded note is geared to track the performance of futures contracts tied to the CBOE Volatility Index, known as the VIX. The benchmark is based on S&P 500 options contracts and rises when investors are seeking protection in the derivatives markets.

After surging above $39 a share in mid-March, iPath S&P 500 VIX Short-Term Futures ETN was trading a little above $29 Friday afternoon. The VIX itself is prone to quick swings after long periods of relative calm.