If the R^2 for the model is high, then there’s nothing wrong. The R^2 for VTSAX in the FF 3-factor model is 99.9% for past 1,3,5 years using daily returns. Situation seems normal.The total US market arguably being concentrated and not fully diversified is a major departure from the usual assumptions in MPT and CAPM. It has implications way beyond just assessing factor fund performance.
The market is a series of unusual situations. Its normal situation is abnormal behavior. The market defies statistical analysis and prediction.
The FF market factor is just the market return minus the risk free return, there’s nothing to break down.
It terms of diversification, don’t just look at ticker symbols, look under the hood. The big tech companies have a lot of diverse technologies under their ticker symbols. As the world gets more high-tech, perhaps there will be the need to split the tech sector into different sectors and merge some of the older sectors.
Statistics: Posted by rkhusky — Fri Oct 17, 2025 7:37 pm — Replies 52 — Views 3351