Since March 11 , when the market 's major indexes were at their lowest levels since hitting multi-year lows in October , the Nasdaq has barreled back 21.2 percent .
Since March 11 , when the market 's major indices were at their lowest levels since hitting multi-year lows in October , the tech-laden Nasdaq has climbed nearly 20 per cent .
is calculated, very simply, as the square root of the variance, as shown in figure 3-5.