How can I calculate cumulative percentage change from beginning period

Question

I am trying to create a DataFrame with a rolling cumulative percentage change. I would like to show the percentage change of the stock from the initial buy date (2014-09-05).

import pandas as pd
import pandas.io.data as web

cvs = web.get_data_yahoo('cvs', '2014-09-05')['Adj Close']

cvsChange = cvs[1:] / cvs.shift(1) - 1

Answer 1

Thank you @EdChum

What I was looking for was...

PriceChange = cvs.diff().cumsum()
PercentageChange = PriceChange / cvs.iloc[0]

Answer 2

How about this:

(cvs.iloc[-1] - cvs.iloc[0]) / cvs.iloc[0] * 100