This post is a slight extension of the previous two articles - Download Stock Data - Part I and Download Stock Data - Part II. We discuss how to produce gross returns, standard deviation and correlation of multiple shares.

In an earlier article, a way to download stock price data files from Google, save it into a local drive and merge them into a single data frame. If files are not large, however, it wouldn't be effective and, in this article, files are downloaded and merged internally.

This article illustrates how to download stock price data files from Google, save it into a local drive and merge them into a single data frame.