The data we’ll use comprise two separate time series: the stream of news stories (text documents), and a corresponding stream of daily stock prices. The Internet has many sources of financial data, such as Google Finance and Yahoo! Finance. For example, to see what news stories are available about Apple Computer, Inc., see the corresponding Yahoo! Finance page. Yahoo! aggregates news stories from a variety of sources such as Reuters, PR Web, and Forbes. Historical stock prices can be acquired from many sources, such as Google Finance