A Simple Binomial Model of Stock Price Movements In a binomial model, the stock price at the BEGINNING of period can lead to only 2 stock prices at the END of that period
The stock Price Assumption Consider a stock whose price is s In a short period of time of length At the change in then stock price S is assumed to be normal with mean Sdt and standard deviation os√△, that is, S follows geometric Brownian motion ds=u Sdt+oSdz Then dInS=( )dt+oda
Example AFI has SOLD for $300,000 a European call on 100,000 shares of a non-dividend paying stock: S 0 =49 =50 r=5%=20% μ=13% T =20 weeks The Black-Scholes value of the option is $240,000 How does the Fl hedge its risk?
Standard Approach to Estimating Volatility (Equation 15.1 Define on as the volatility per day between day n-1 and day n, as estimated at end of day n-1 · Define, as the value of market variable at end of day i Define ui= In(S /Si-1)
