Inability to hedge against changes in this quantity motivated a model created by Brenner and Galai. This quantity names a “tax” that Mark Spitznagel describes as crushing long-term CAGRs. Up-factors and down-factors in a binomial pricing model are determined by time and this quantity. This quantity is plotted versus “moneyness” and “time to maturity” to form its namesake surface. (15[1])Some (15[1])“Bastard (15[1])Greeks” reflect changes in this quantity, a measure of which is (15[1])multiplied by Gamma and the price squared in the (*) Black–Scholes equation. Plotting the “implied” form of this (10[1])quantity (10[1])against strike price (10[1])can produce this quantity’s namesake “smile.” (10[2])The “historical” (10[1])form (10[1])of this quantity equals the standard deviation of the logarithmic returns of a financial instrument. For 10 points, name this quantity that measures the variation in the price of a financial instrument over time. ■END■ (0[2])