Financial engineers and quantitative analysts often exploit network services to retrieve stock quotes.  A large number of services exist, including paid-for real-time feeds from Bloomberg and Reuters.  Yahoo, however, provide a free service that is delayed by fifteen minutes.

The Interactive Stock Quote Importer in this worksheet will import quotes (including historical data) from Yahoo for a series of user-specified NYSE stock symbols.  This application

Within Maple, the data is summarised in a table, or can be accessed as variables.  If, for example, GSK has been specified, simply type in GSK[ and then press CTRL+SPACE for a list of accessible properties.  Several examples are given below the Importer.

The worksheet concludes by optimizing an asset portfolio by maximising the Sharpe Ratio with imported historical data.

The applications of this worksheet include ranking companies by financial information (i.e. earnings per share, market capitlization etc), plotting historical data, generating moving averages, and optimizing asset portfolios.  

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The Sharpe ratio quantifies how effectively a portfolio of risky assets uses risk to maximise return.  It is defined as follows.

The expected portfolio return is predicted from historic data, the standard deviation of the asset mix is traditionally used as a proxy for risk (or volatility) and the risk free return is the return that can be expected from a zero-risk investment (i.e. the interest on US Treasury Bills or the redemption yield on UK gilts).  A higher Sharpe Ratio essentially signifies a more risk efficient portfolio.

For a stock mix of GSK, XOM, WMT and KO, the asset mix that maximizes the Sharpe Ratio is

Hence the portfolio composition that best uses risk to maximize return consists of 74% XOM, 23% WMT and 3% KO.  This calculation is sensitive to the data used.