VXAPL (Cboe APPLE VIX)
The Cboe APPLE VIX IndexSM (VXAPL) is a VIX®-style estimate of the expected 30-day volatility of APPLE stock returns. Like VIX, VXAPL is calculated by interpolating between two weighted sums of option midquote values, in this case options on APPLE. The two sums essentially represent the expected variance of the APPLE returns up to two option expiration dates that bracket a 30-day period of time. VXAPL is obtained by annualizing the interpolated value, taking its square root and expressing the result in percentage points.