Motivation

Many retirees are anxious about how much they can spend from their retirement assets each year and avoid later running out of funds. I know the feeling, as I have been there myself. Many years ago, I unexpectedly faced early retirement.

There were some investments, a pension, and future Social Security. But how much could I spend each year? Could I keep on living as I had been, or did I need to undertake some serious retrenchment?

Unlike most in such a predicament, I should have known the answer. Earlier, I had been a financial economist as a tenured professor at the University of California, Berkeley. In fact, at that time I published a paper in the American Economic Review with an academic solution to such a problem. The title was, “Lifetime Portfolio Selection in Continuous Time for a Multiplicative Class of Utility Functions.”

My experience, however, had not just been academic. I also had practical experience as a business economist. For 10 years I headed up the economics area at a New York bank.

None of this experience, however, seemed of much help. I had no clue as to whether I needed to undertake some serious retrenchment, or whether I could continue living as I had been. But if I didn’t know the answer, presumably I wasn’t the only one. Finding an answer was clearly a worthy topic for some serious research.

The solution I developed is called the Retrenchment Rule. The Retrenchment Rule obtains optimal limits on the amount that can be withdrawn each year. These limits depend on the remaining value of the assets and the longest that additional withdrawals might be required at any time. This solution can be used not only by individuals making withdrawals over retirement, but also to manage the assets in a trust  This is a trust for which the beneficiary might be an individual of any age, or a nonprofit organization.

An overview of the solution based on finding optimal limits for the drawdowns that can be made at any time is provided in a paper at this site. This paper is called, “Optimal Wealth  Drawdowns”. It is available by clicking on Decumulation.

An application to managing a trust portfolio called, “Disbursements” appears in the Journal of Portfolio Management (Spring 2017). This application assumes that the initial disbursement from a trust can be reduced to a reasonably sustainable level in real terms for the long run without undue hardship on the beneficiary. Subsequently, however, investment returns may turn out to be much worse than expected. Reducing the disbursements will require retrenchment by the beneficiary, but continuing the disbursements at the current level may exhaust the funds in the portfolio. The Retrenchment Rule is needed to determine whether a reduction in the disbursements is necessary at any time, and if so by how much.

Earlier work applying the Retrenchment Rule to drawing down assets over retirement is in a book called: The Retrenchment Rule: When It’s Too Late to Save More for Retirement. It is available on Amazon.

The Contents and Chapter 1 of the book are available at this site. This introductory chapter applies the system using as an example annual returns that were actually realized in the past on investments in the U. S.. These results are compared to alternatives that might have been used to drawdown investments. This introductory chapter also contains a brief chapter-by-chapter summary of the book. The Contents and Chapter 1 of the book are available by clicking on Book and Chapter 1.

Many are not ready to retire, and are in the process of accumulating assets for that purpose. A paper at this site uses simulated investment returns to develop efficient strategies for accumulating assets for retirement or other purposes. This paper is called, “Efficient Wealth Accumulation”. It is available by clicking on Accumulation.

Further details of my background can be found in Biography. Earlier papers I have written on retirement and other topics are given in Papers. If you have any questions or comments about items at this site please email me at Contact.