Black Scholes Merton Model
A mathematical model of a financial market which contains derivative investment instruments is called as Black Scholes Merton model [1]. This model provides simple formula regarding asset's price and its volatility, time to maturity of the contract and the risk free interest rate [2]. Black Scholes formula gives a theoretical estimate of the price of European-style options [1].
Let
 = Asset Price 
						 = Exercise Price 
						 = Risk Free Rate 
						 = Time to expiration 
						 = Standard deviation 
						 = The cumulative distribution function of the standard normal distribution 
						 = The standard normal probability density function
 = Price Call 
							 = Price Put
 = Delta Call 
								 = Delta Put
 = Gamma Call 
									 = Gamma Put
 = Theta Call 
										 = Theta Put
 = Vega Call 
											 = Vega Put
 = Rho Call 
												 = Rho Put
We have
Example 1
Input
Asset Price = 125.94 
													Exercise Price = 125 
													Time to Expiration = 1 
													Standard Deviation = 83% 
												Risk Free Rate = 4.46%
Output
Price Call: 42.776, Price Put: 36.383 
													Delta Call: 0.684, Delta Put: -0.316 
													Gamma Call: 0.003, Gamma Put: 0.003 
													Theta Call: -20.534, Theta Put: -15.202 
													Vega Call: 44.824, Vega Put: 44.824 
												Rho Call: 43.316, Rho Put: -76.232
Example 2
Input
Asset Price = 460 
													Exercise Price = 470 
													Time to Expiration = 0.17 
													Standard Deviation = 58% 
												Risk Free Rate = 2%
Output
Price Call: 40.105, Price Put: 48.509 
													Delta Call: 0.517, Delta Put: -0.483 
													Gamma Call: 0.004, Gamma Put: 0.004 
													Theta Call: -132.91, Theta Put: -123.541 
													Vega Call: 75.592, Vega Put: 75.592 
												Rho Call: 33.65, Rho Put: -45.979
1. Black–Scholes model. (n.d.). Retrieved August 18, 2016, from https://en.wikipedia.org/wiki/ Black–Scholes_model
2. Black-Scholes-Merton approach – merits and shortcomings. (n.d). Retrieved June 13, 2017 from https://www.essex.ac.uk/economics /documents/eesj/matei.pdf
Capital Asset Pricing Model (CAPM)
In finance, determination of a theoretically appropriate required rate of return of an asset is called as capital asset pricing model (CAPM). This method provides to make decisions about adding assets to a portfolio which is well-diversified [1].
					Let 
					\(E(R_s)\) = Expected Stock Return 
					\(E(R_m)\) = Expected Market Return 
					\(r_f\) = Risk Free Rate 
					\(\beta\) = Beta
				
We have
Example 1
Input
Expected Return on Stock = 14% 
					Expected Return of the Market = 12.6% 
				Beta = 1.6
Output
Risk Free Rate = 10.267%
Example 2
Input
Expected Return of the Market = 4% 
					Risk Free Rate = 2.7% 
				Beta = 1.7
Output
Expected Return on Stock = 4.91%
1. Capital asset pricing model (n.d.). Retrieved August 18, 2016, from https://en.wikipedia.org/wiki/ Capital_asset_pricing_model
Dividend Discount Model (DDM)
The dividend discount model (DDM) is a method which values a stock price of a company based on the future dividends' net present value (npv) [1].
Gordon Model
One of the class of dividend discount model is the Gordon Model which assumes dividends will increase at a constant growth rate [2].
Let
 = Dividend 
		 = Growth Rate 
		 = Required Rate of Return
= Price
If the given dividend is the current dividend, then
If the given dividend is the next dividend, then
Example 1
Input
Dividend Type = Current 
			Dividend = 4.56 
			Required Rate of Return = 13.49% 
		Growth Rate = 5.97%
Output
Price of Stock = 64.258
Example 2
Input
Dividend Type = Next 
			Dividend = 5.93 
			Required Rate of Return = 8.16% 
		Growth Rate = 1.25%
Output
Price of Stock = 85.818
1. Dividend discount model (n.d). Retrieved June 13, 2017 from https://en.wikipedia.org/ wiki/Dividend_discount_model
2. Stock valuation. (n.d.). Retrieved August 18, 2016, from https://en.wikipedia.org/ wiki/Stock_valuation
Nonconstant Growth Stock Calculation
We know that Gordon Model assumes that dividends will rise at a constant growth rate. However, companies' growth rate is not always constant. Nonconstant growth model is a more general method than the Gordon Model and it is based on assuming growth rates are nonconstant until a point, then tehy are constant after that point [1].
Let 
				 = Price of Stock 
				 = Value of Stock at time i 
				 = Expected Dividend at time i 
				 = Number of Periods 
				 = Growth rate at time i 
				 = Required return on Stock at time i. 
				 = Required return until time i
First, define
 = 1 
					
If i < N, then
If i = N, then
Hence, we have
Example 1
Input
Dividend = 2 
					Period = 4
Required Rate of Return 1 = 12% 
					Growth Rate 1 = 8%
Required Rate of Return 2 = 12% 
					Growth Rate 2 = 4%
Required Rate of Return 3 = 12% 
					Growth Rate 3 = 5%
Required Rate of Return 4 = 12% 
					Growth Rate 4 = 6%
Output
Price of Stock = 35.06
Example 2
Input
Dividend = 10 
					Period = 3
Required Rate of Return 1 = 12% 
					Growth Rate 1 = 8%
Required Rate of Return 2 = 12% 
					Growth Rate 2 = 4%
Required Rate of Return 3 = 12% 
					Growth Rate 3 = 5%
Output
Price of Stock = 152.91
1. Stock valuation. (n.d.). Retrieved August 18, 2016, from https://en.wikipedia.org/ wiki/ Stock_valuation
Weighted Average Cost of Capital (WACC)
A compony needs to know how to finance its assets to pay to all its security holders, so that weighted average cost of capital (WACC), which is also defined the cost of capital, is the rate that a company is expected to pay on average to all its security holders. WACC can be used by companies to see whether the investment projects are worth to undertake or not [1].
Let 
					 = Equity 
					 = Cost of Equity 
					 = Debt 
					 = Cost of Debt 
					 = Corporate Tax Rate
= Weighted Average Cost of Capital
We have
Example 1
Input
Cost of Equity = 15% 
						Equity = 400,000 
						Cost of Debt = 8% 
						Debt = 600,000 
					Corporate Tax Rate = 5%
Output
Weighted Avg Cost of Capital = 10.56%
Example 2
Input
Cost of Equity = 12.5% 
						Equity = 8000 
						Cost of Debt = 6% 
						Debt = 2000 
					Corporate Tax Rate = 30%
Output
Weighted Avg Cost of Capital = 10.84%
1. Weighted average cost of capital (n.d.). Retrieved August 18, 2016, from https://en.wikipedia.org/ wiki/Weighted_average_cost_of_capital
Holding Period Return (HPR)
Holding period return (HPR) is defined as the total return on an asset or portfolio over a time when it was held.
In finance, holding period return (HPR) is the total return on an asset or portfolio over a period during which it was held. It is called as the simplest and most significant measures of investment performance [1].
Let
 = Initial Value 
					 = Ending Value 
					 = Income 
					 = Holding Period Return
We have
Example 1
Input
Initial Value = 50 
						Ending Value = 60 
					Income = 5
Output
Holding Period Return = 30%
Example 2
Input
Initial Value = 200 
						Ending Value = 320 
					Income = 10
Output
Holding Period Return = 65%
1. Holding period return. (n.d.). Retrieved August 18, 2016, from https://en.wikipedia.org/ wiki/Holding_period_return
Expected Return
Expected return can be calculated using the probability states and expected return states. It measures the center of the variable's distribution [1].
Let 
					 = Expected Return 
					 = Standard Deviation 
					 = Expected Return in state i 
					 = Probability of state i 
					 = The Number of States
We have the following formulas:
Example 1
Input
Period = 4
State 1 - Probability: 20%, Stock A: 5%, Stock B: 10% 
						State 2 - Probability: 30%, Stock A: 10%, Stock B: 15% 
						State 3 - Probability: 30%, Stock A: 15%, Stock B: 20% 
					State 4 - Probability: 20%, Stock A: 20%, Stock B: 25%
Output
Expected Return (A): 12.5% 
					Standard Deviation (A): 5.123%
Expected Return (B): 17.5% 
					Standard Deviation (B): 5.123%
Example 2
Input
Period = 4
State 1 - Probability: 15%, Stock A: 5%, Stock B: 10% 
						State 2 - Probability: 35%, Stock A: 15%, Stock B: 20% 
						State 3 - Probability: 35%, Stock A: 25%, Stock B: 30% 
					State 4 - Probability: 15%, Stock A: 35%, Stock B: 40%
Output
Expected Return (A): 20% 
					Standard Deviation (A): 9.22%
Expected Return (B): 25% 
					Standard Deviation (B): 9.22%
1. Expected return (n.d.). Retrieved August 18, 2016, from https://en.wikipedia.org/ wiki/Expected_return