How to Solve the Curse of Dimensionality With Dynamic Programming

In this episode I speak with Martin Tarlie, a member of the Asset Allocation team at GMO and spearheading their work on Nebo, a goals-based investment platform.

Martin describes Nebo as, “bridging the gap between financial planning and portfolio management,” with a key innovation being the reformulation of risk from volatility to not having what you want/need when you want/need it. In other words, constraints on both wealth target and horizon.

This reformulation of the core problem introduces a number of complications to the portfolio optimization process. For example, under classic power utility, lower volatility is always preferred. But if you’re an investor expecting significant shortfall with respect to your wealth targets, increased volatility may be something very much worth pursuing.

We spend plenty of time in the weeds discussing topics such as: the limitations of dynamic programming via backwards indication, the term structure of return variance, ergodicity economics, and portfolio selection sensitivity to utility function choices. And while these are all important details, at the end of it all, what Martin stresses most is that it’s the reformulation of the problem being solved that ultimately leads to a more pragmatic solution for allocators.

Please enjoy my conversation with Martin Tarlie.