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Analyzing the theoretical value of call options for AAPL after the iPhone X announcement and comparing it with the put-call parity and Black-Scholes models.
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Financial Options & Option Valuation REVISITED Week 7 IMBA 2017 ACF FALL 1 CLASS ASSIGNMENT SOLUTION
Class assignment (hand in) • Consider AAPL after the iPhone X announcement:
Required: 1) Calculate the theoretical value of the Call Option X=$155 listed at market price $8.70 Assume: So=$ 161, X=$155, Rf=3% per year, Su=$200 and Sd=$120 2) Use the put call parity to calculate the P(ut) value with X=$155 for expiration 27 Oct. 2017 3) Use the BS model to calculate C and P and compare the above values: what is your conclusion? Note the dividend yield on AAPL stock is 1.56% (DPS/stock price) Market values : C= $8.70 and P= $2.68
Solution… 1) Calculate the theoretical value of the Call Option X=$155 listed at market price $8.70 Assume: So=$ 161, X=$155, Rf=3% per year, Su=$200 and Sd=$120 Hedge Ratio: (Cu-Cd)/(Su-Sd)= ($45-$0)/($200 - $120)=$45/$80=9/16 (buy 9 stocks AAPL and sell 16 calls) Set up the table and find: -$1449+16C+$1080/(1.0034)=0 so C= $23.29 Note 3% per year is about 0.34% per 41 days (the option expires 27 october 2017) today is 16 september 2017
2) Use the put call parity to calculate the P(ut) value with X=$155 for expiration 27 Oct. 2017 • Put Call Parity we found in class: • P=C-So+PV(X)+PV(dividends) • Note that option prices for stocks are effected by dividends on stocks…(see the BS model for instance) • You found C=$23.29 in 1) • P= $23.29-$161+$155/1.0034+(1.56%*$161* 41/365)/1.0034= • To be entirely correct we will need to consider what part of the dividend is actually paid between 16 september and 27 october… • Above equation leads to: P=$13.06
3) Use the BS model to calculate C and P and compare the above values: what is your conclusion? Note the dividend yield on AAPL stock is 1.56% (DPS/stock price) All the data were given your only task is to fill them in in the YELLOW area. Note the dividend yield is put in as a ratio, the time to expiration is 41/365, the standard deviation is in the option price table last column “volatility”…. Use the EXCEL file that was sent to you… REMINDER: Bring it for the final exam…
You have 3 prices for C and P Of course you trust the market BUT the BS model came quite close. The Binomial model offers very high values due to the assumed high STDEV of ($200 - $ 120) some students used the BS EXCEL to see at what STDEV the model predicts a C=$23.29 and found: 95.4%... (see next page)
AAPL’s STDEV is high but not 95% so we don’t trust this result….