A stock's volatility under EWMA is estimated at 3.5% on a day its price is $10. The next day, the price moves to $11. What is the EWMA estimate of the volatility the next day? Assume the persistence parameter λ = 0.93.
Recall the formula for calculating variance under EWMA. See below. Therefore the correct answer is =SQRT((1 - 0.93)*(LN(11/10))^2 + 0.93*((3.5%^2))) = 4.21%. Other answers are incorrect. Note that continuous returns are to be used, ie ln(11/10) and not discrete returns (=1/10) - though generally the difference between the two is small over short time periods. (If in the exam the answer doesn't exactly match, try using discrete returns.)
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