Saturday, 13 May 2017

Predicting Retirement Financial Success

One of the negatives to using a Safe Withdrawal Rate (SWR) model, such as the 4% Rule, to predict when early retirement is possible and to guide spending in retirement is that if history repeats you could leave a lot of wealth on the table.  This is because if a conservative SWR is chosen it tends to have very few historic sequence of returns that fail meaning the withdrawal rate you choose is based on some of the worst sequence of returns rather than the best.

Let me demonstrate with an example.  Let’s enter retirement with $1,000,000, a portfolio that is 75% US Equities : 25% Bonds, expenses of 0.18% and a retirement period of 30 years.  Plug that into cFIREsim and you get the following historic sequence of returns:

4% Rule Sequence of Returns for a 75% Equity : 25% Bond Portfolio
Click to enlarge, 4% Rule Sequence of Returns for a 75% Equity : 25% Bond Portfolio

After 30 years that $1,000,000 has in Real (ie after inflation) terms become an average of $2,027,248 and a median of $1,531,784 while the highest wealth value is $5,957,932 and the lowest is -$370,926.  So in the one extreme you’re living under a railway arch begging for food and in the other you have nearly six times what you started with.  If history were to repeat could we potentially be more precise than that?