The risk is an indicator for trading, short to mid term wise (we are talking about 1-3 weeks time frame here), Nasdaq would be less risk to take position compared to Dow and S&P in this case.  However it doesn't mean Nasdaq is a better investment than the other two.  You can have something very risky and very good for investment and something very low risk all the time but very bad for investment.  Remember we need to factor in time when we do investment.  For example, we can buy something at very low risk and cheap but it doesn't appreciate overtime.  Is this a good investment?  Definitely not.