Introduction to Financial Concepts in Python
Dakota Wixom
Quantitative Finance Analyst
$$ \text{Return (\% Gain) } = \frac{v_{t_2} - v_{t_1}}{v_{t_1}} = r$$
$$ \frac{\$11,000 - \$10,000}{\$10,000} * 100 = \text{10\% annual return (gain) on your investment} $$
$$ v_{t_2} = v_{t_1} * (1 + r) $$
$$ \text{\$10,000} * (1 + \frac{10}{100}) = \text{\$11,000} $$
$$ \text{Investment Value} = v_{t_0}*(1 + r)^t $$
If the growth rate $r$ is negative, the investment's value will depreciate (shrink) over time.
$$ df = \frac{1}{(1 + r)^t} $$
$$ v = fv*df $$
$$ \text{Investment Value} = v_{t_0}*(1 + \frac{r}{c})^{t*c} $$
Consider a $1,000 investment with a 10% annual return, compounded quarterly (every 3 months, 4 times per year):
$$ \$1,000*( 1 + \frac{0.10}{4} )^{1*4} = \$1,103.81 $$
Compare this with no compounding:
$$ \$1,000*( 1 + \frac{0.10}{1} )^{1*1} = \$1,100.00 $$
Notice the extra $3.81 due to the quarterly compounding?
Compounded Quarterly Over 30 Years:
$$ \$1,000*(1 + \frac{0.10}{4})^{30*4} = \$19,358.15 $$
Compounded Annually Over 30 Years:
$$ \$1,000*(1 + \frac{0.10}{1})^{30*1} = \$17,449.40 $$
Compounding quarterly generates an extra $1,908.75 over 30 years
Introduction to Financial Concepts in Python