Adding onto the growing interest for low-volatility exchange traded fund strategies, Invesco PowerShares is planning two more low-volatility products that slice into the U.S. equity market.

According to a recent SEC filing, PowerShares is working on the PowerShares S&P 400 Low Volatility Portfolio and PowerShares S&P 600 Low Volatility Portfolio. No tickers or expense ratios were provided.

The S&P 400 Low Volatility Portfolio will try to reflect the performance of the S&P MidCap 400 Low Volatility Index, which include 80 securities that have the lowest volatility over the past 12 months out of the 400 medium capitalization securities.

The S&P 600 Low Volatility Portfolio tries to reflect the performance of the S&P SmallCap 600 Low Volatility Index, which include 120 securities that have the lowest volatility over the past 12 months out of the 600 small capitalization securities.

The two proposed funds will add to the firm’s highly successful PowerShares S&P 500 Low Volatility Portfolio (NYSEArca: SPLV), which launched in early 2011 and has since gathered $3.2 billion in assets.

Low-volatility stocks have posted higher risk-adjusted returns during uncertain market conditions. However, the asset class tends to underperform during a bull market. Morever, low-volatility picks have also been regarded as a safe-haven asset as investors move out ow low yielding government bonds and into boring stocks with above-average dividends. [Low-Volatility ETFs: The New Safe Haven]

PowerShares also recently launched another type of low-volatility ETF, the PowerShares S&P 500 Downside Hedged ETF (NYSEArca: PHDG). [A Closer Look at Two New Volatility-Hedged ETFs]

Other low-volatility ETFs include:

  • iShares MSCI All Country World Minimum Volatility (NYSEArca: ACWV)
  • iShares MSCI USA Minimum Volatility (NYSEArca: USMV)
  • iShares MSCI Emerging Markets Minimum Volatility (NYSEArca: EEMV)
  • PowerShares S&P International Developed Low Volatility (NYSEArca: IDLV)
  • PowerShares S&P Emerging Markets Low Volatility (NYSEArca: EELV)
  • Direxion S&P 500 DRRC Volatility Response Shares (NYSEArca: VSPY)

For more information on low-volatility funds, visit our low-volatility category.

Max Chen contributed to this article.