Update : Oct. 29, 2012
A Risk Control Indicator is an index expressing income from an investment strategy which reduces deviations in income by adjusting cash holding ratio of an investment portfolio tracking a certain indicator (hereinafter "underlying indicator") as needed, according to certain standards.
This type of indicator is generally a type of Enhanced Indicator (an index which expresses an investment strategy pursuing certain investment results for a certain investment strategy).
The following is a specific explanation of the traits of Risk Control Indicators.
Investment portfolios tracking TOPIX (Tokyo Stock Price Index) are composed of the approximately 1,700 issues listed in the TSE 1st Section. In the case of the "TOPIX Risk Control Indicator", which uses TOPIX as an underlying index, the cash portion (interest is reflected) of the portfolio would also be added. Because the cash portion, excluding interest, does not experience price movements, the income deviation (price movement or volatility) of the overall portfolio is suppressed in comparison to a portfolio composed of 100% stock holdings.

Thus, at times when the underlying indicator TOPIX volatility (price movement) is at a maximum, such as large market gains or losses, the TOPIX Risk Control Index is able to suppress volatility to a greater extent than the underlying index by increasing the cash portion of portfolio holdings.
As displayed in the graph below, when TOPIX is rapidly declining or rising, the TOPIX Risk Control Index does not experience large fluctuations in either direction, demonstrating its comparatively stable price movements.

When compared to an ETF tracking the underlying indicator, ETFs tracking a Risk Control Indicator hold a cash portion as part of their portfolios, causing smaller daily price movements. Accordingly, profits resulting from gains in the underlying indicator will be smaller than those from the underlying indicator. Additionally, losses resulting from a drop in the underlying indicator will be smaller than those from the underlying indicator.
While Risk Control Indicators can be expected to reduce losses at times when the market is down, they also limit profits from rises in stock price. (Compared to the underlying indicator, both profit/loss are limited.) Therefore, please be aware that expected results may be difficult to achieve when investing for short-term returns.