A quick note on the recent market rally here of late. It's plain to see the markets have been on a tear for the month of June (and going back into May for the QQQ) as the SPY closed today at its highest level in almost fourteen months. If we start to look at the historical levels, however, it appears the SPY may be overbought in the short-run and susceptible to a mean-reverting pattern. Here's the daily chart of the SPY as of today's (6/15/23) close... When looking at the distance between the closing price and the 50-day moving average (illustrated by the yellow bar), we're noticing a large gap... this can be measured by a statistic I developed which I casually refer to as "variance"... or the distance between current prices and their respective moving averages. Historically, throughout the life of the SPY (which debuted in January of '93), the variance over the 50-day moving average has peaked at a reading of 3.20... today's reading posts up at 2.49...
"The 'radical' of one century is the 'conservative' of the next." -Mark Twain In this series, I'm going to explore some of the advances in portfolio management, construction, and modeling since the advent of Harry Markowitz's Nobel Prize winning Modern Portfolio Theory (MPT) in 1952. MPT's mean-variance optimization approach shaped theoretical asset allocation models for decades after its introduction. However, the theory failed to become an accepted industry practice, so we'll explore why that is and what advances have developed in recent years to address the shortcomings of the original model. The Black-Litterman Formula The Black-Litterman formula incorporates two distinct inputs; the first is the Implied Equilibrium Return Vector we constructed in Part 1, the second is a series of vectors and matrices that incorporate a manager's views/forecasts of the market. The product of the formula is an updated Combined Expected Excess Return ...