VIX exchange-traded-funds (ETFs) track the performance of the CBOE Volatility Index, a gauge that measures expectations for future price fluctuations in the stock market based on the implied volatility of S&P 500 Index options. They allow investors to speculate on market swings via a single investment product without having to directly trade complex derivative products, such as options or futures. As The VIX index typically has an inverse correlation to the S&P 500, investors can also use these funds to hedge against market sell-offs during times of market uncertainty.

Before trading VIX ETFs, investors should be aware of the effects of contango. This simply means that the value of these funds erode over time as they regularly roll from cheaper near-term futures contracts to more expensive longer-term contracts. Therefore, the ETFs are designed for short-term tactical trading, rather than for seeking long-term exposure to the VIX index.

Below, we discuss three top VIX ETFs, excluding inverse and leveraged ETFs, as well as funds with less than $30 million in assets under management (AUM). The first two funds provide exposure to VIX short term futures, while the third fund allow investors to play volatility using mid-term VIX futures. All data below is as of Dec. 15.

iPath Series B S&P 500 VIX Short-Term Futures ETN (VXX)

• Performance Over One-Year: -72.27%
• Expense Ratio: 0.89%
• Annual Dividend Yield: N/A
• Three-Month Average Daily Volume: 9,537,757
• Assets Under Management: $284.38 million
• Inception Date: Jan. 19, 2018
• Issuer: Barclays Capital Inc.

The fund, structured as an exchange-traded note (ETN), aims to provide a similar return to the S&P 500 VIX Short-Term Futures Index, a benchmark that tracks first- and second-month futures contracts tied to the CBOE Volatility Index. VXX's narrow penny spreads and daily reset feature make it ideal for investors seeking to capitalize on short-term market volatility. However, the daily reset mechanism also means the fund's longer-term returns substantially deviate from the VIX index over time.

ProShares VIX Short-Term Futures ETF (VIXY)

• Performance Over One-Year: -72.52%
• Expense Ratio: 1.05%
• Annual Dividend Yield: N/A
• Three-Month Average Daily Volume: 3,511,001
• Assets Under Management: $161.38 million
• Inception Date: Jan. 3, 2011
• Issuer: ProShares

VIXY tracks the same underlying index as the first fund, the S&P 500 VIX Short-Term Futures Index, and is structured similarly. The key differences primarily relate to management fees and trading liquidity. Although VIXY has a slightly higher expense ratio than VXX, it's not overly important as these funds are only designed for short-term plays on volatility. Moreover, while VIXY turns over fewer shares than the first fund, it still provides ample liquidity to easily enter and exit trading positions.

ProShares VIX Mid-Term Futures ETF (VIXM)

• Performance Over One-Year: -46.01%
• Expense Ratio: 0.98%
• Annual Dividend Yield: N/A
• Three-Month Average Daily Volume: 85,171
• Assets Under Management: $36.39 million
• Inception Date: Jan. 3, 2011
• Issuer: ProShares

The ETF attempts to replicate the performance of the S&P 500 VIX Mid-Term Futures Index, a benchmark tracking the CBOE Volatility Index with contracts averaging five months until expiration. VIXM provides a point of difference to the first two funds by allowing investors to speculate on the S&P 500's volatility in upcoming months rather than over the next 30 days. It's worth noting that this fund has an average daily trading volume of less than 100,000 shares, which may increase transaction costs, such as slippage. Under normal market conditions, the ETF has an average spread of 0.16%.

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As of the date this article was written, the author does not own any of the above securities.