Mastering Python for Finance

Calculating the price of a bond

When the YTM is known, we can get back the bond price in the same way we used the pricing equation investigated earlier. Save the code as bond_price.py:

""" Get bond price from YTM """
def bond_price(par, T, ytm, coup, freq=2):
    freq = float(freq)
    periods = T*freq
    coupon = coup/100.*par/freq
    dt = [(i+1)/freq for i in range(int(periods))]
    price = sum([coupon/(1+ytm/freq)**(freq*t) for t in dt]) + \
            par/(1+ytm/freq)**(freq*T)
    return price

Plugging in the same values from the earlier example, we get the following result:

>>> from bond_price import bond_price
>>> bond_price(100, 1.5, ytm, 5.75, 2)
95.0428

This gives us the same original bond price discussed in the earlier example. Using the bond_ytm and bond_price functions, ...