ProShares launched the first two U.S.-listed VIX-related ETFs, the ProShares VIX Short-Term Futures (NYSEArca: VIXY) and ProShares VIX Mid-Term Futures (NYSEArca: VIXM), earlier in 2011.

It should be noted that the new funds will only meet their target on a daily basis. As a result of compounding of daily returns, returns over a longer period will differ from the benchmark target returns. Also, they follow VIX futures, not the spot price. [Volatility-Linked ETFs Rise to 2011 High]

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Max Chen contributed to this article.