One margin such an investor must consider is the choice between:But, again, I must warn against paying too much in fees to active mutual fund managers. Look into investor-friendly passively managed index funds provided by companies such as Vangaurd. The book by Swenson that I mentioned in my previous post is an excellent one, though it will probably be challenging for a financial n00b.
(1) investing in a diversified portfolio of equities, reinvesting payouts and rebalancing periodically to maintain diversification;
(2) investing in short-term safe bills, rolling the portfolio over into similar short-term debt instruments as pieces of it mature.
The marginal investor must expect that their marginal dollars would be equally attractively employed in each of these strategies.
Figure 1 [in the PDF] plots the cumulative return distribution for the relative returns for these two twenty-year portfolio strategies starting in each year since the start of the twentieth century. The average geometric return differential since 1901 is some 4.9 percent per year. When the portfolios are cashed in after twenty years, investments in diversified stock portfolios are on average 2.67 times as large as an investment in short-term Treasury bills after twenty years. Stock investors more than double their relative wealth 60 percent of the time, more than quadruple their relative wealth 30 percent of the time, and have a 17 percent chance of a more than seven-fold multiplication of relative wealth. The downside is small: the empirical CDF finds that stocks do worse than bills less than 9percent of the time. The very worst case observed is the 20 years starting in 1965, when investing in stocks yields a relative cumulative wealth loss of 17 percent compared to investing in bills.
Here are some quotes from David Swensen, who runs Yale's endowment: The above quote represents the generally-accepted wisdom on the subject. However, Swenson makes the point: By "real" appreciation, he's taking inflation into account. The data cited in the previous quote does not do so. These quotes are from his excellent book, Unconventinal Success.
There is also some good data out there that looks backwards at 20-year investment periods and shows that, while the results are generally good, there are definitely periods when equities were mediocre investments. I'll see if I can find a good reference.
And we haven't even started on the topic of return degradation from unnecessary mutual fund fees, tax distributions and transaction costs.
posted by mullacc at 7:55 PM on April 4, 2008 [1 favorite has favorites]