The Hirschman-Herfindahl Index (HHI) is a measure of market concentration, typically used in economics to see if there is a monopoly in a certain market. However, here I apply it to investments in a total portfolio to see the concentration. If ms_x = (total for investment x / total sum of all investments in portfolio), then HHI = sum of ms^2 over the ms's of all investments in the portfolio. Note, I use "ms" for "market share". If your portfolio has N investments, the HHI ranges from ((1/N)*10000)/100 = 100/N to a maximum of 10,000. See http://www.investopedia.com/terms/h/hhi.asp I also compare current real-time numbers to a snap-shot of the portfolio from the past so I can calculate the differences in the sums as well as in the HHIs to see change in the portfolio over time. Note, the numbers I have in the spreadsheet are fictitious for me, as are some of the investment categories or the number of investment categories. Regarding investing: I do not provide personal investment advice and I am not a qualified licensed investment advisor. I am an amateur investor. All information found here, including any ideas, opinions, views, predictions, forecasts, commentaries, suggestions, expressed or implied herein, are for informational, entertainment or educational purposes only and should not be construed as personal investment advice. While the information provided is believed to be accurate, it may include errors or inaccuracies. I will not and cannot be held liable for any actions you take as a result of anything you read here. Conduct your own due diligence, or consult a licensed financial advisor or broker before making any and all investment decisions.

• published: 15 Feb 2014
• views: 8