Questions newcomers to this model commonly ask. Click any question to expand the answer.
+Can I trade exactly the way the analysis suggests?
No, that is not recommended. Every analysis here is a statistical estimate based on historical market data, and it does not guarantee future returns or losses. Trading costs, taxes, FX costs, market impact, and your own investment goals and horizon are also not reflected. Use the results as a diagnostic of "what kind of risk and return profile this portfolio has", and before any real investment decision review your own situation and consider consulting a qualified professional.
+I re-ran the analysis on the same tickers but the result is slightly different — why?
That is expected. Each run fetches the latest prices from yfinance and recalculates. When new trading days arrive or the factor data is updated between runs, the sample changes and the means, variances and regression coefficients shift slightly. The risk-free rate used for the Sharpe ratio (the US 13-week T-bill yield) is also refreshed daily. If the change is large (e.g. alpha flips sign, or a beta moves more than 0.3), the sample may be too short for stable results — check the analysis reliability score at the top of the result page.
+How are Korean and US stocks handled together?
Holding amounts are converted to KRW at the FX rate at analysis time to set the weights. Returns, however, are calculated from each holding's local-currency price, so the returns and volatility of US holdings do not include KRW/USD exchange-rate moves. If you invest in won, your actual account can swing more or less than shown, by the amount the exchange rate moves. Markowitz and HRP analyze holdings from both markets as one portfolio. Fama–French (3- / 5-factor) regresses Korean holdings on DIVA's own Korea factors and US holdings on factors from the Kenneth French Data Library, then combines the two by portfolio weight into a single result.
+How is the "analysis reliability" score calculated?
A 0–100 measure of how much the numbers could shift because of limited data or chance (not whether the portfolio is good). For Markowitz and HRP it averages ① the risk estimate (data window, and window length relative to the number of holdings) and ② the return estimate (the 95% error range of the past average return), so the same portfolio over the same window scores the same in both. Fama–French averages the beta estimate (window and beta error range) and explanatory power (R²). 75+ reliable, 55+ worth referencing, 35+ read conservatively, below that interpret with care. A heuristic for reference, not an academic standard.
+Why does a significant 3-factor alpha lose significance under the 5-factor model?
Very common — and arguably a healthy sign. Part of the 3-factor alpha was actually exposure to RMW (profitability) or CMA (investment). When you add those two factors, that part is attributed to factor contribution, the residual "alpha" shrinks, and the standard error shifts so significance can disappear. If R² rose from 3F to 5F (it usually does), the 5-factor model has sharper explanatory power, and the earlier alpha was likely unmeasured factor exposure rather than genuine skill.
+My value and size betas differ between the 3-factor and 5-factor results for the same portfolio. Which is right?
Both are correct within their own model. The 5-factor model adds the profitability (RMW) and investment (CMA) factors, which tend to move with the existing ones — value and investment especially. So part of what the 3-factor model attributed to value beta moves to investment beta under five factors, and the overlap widens the error on individual betas. If a beta that was significant under three factors loses significance in the 5-factor coefficients, that signals overlap with the new factors; read that beta for its sign and rough size only.
+What changes most in interpretation once RMW and CMA are added?
You get to separate "profitability" and "investment style" effects. A Buffett-style basket of high-quality, conservatively-investing companies looks like "just positive alpha" under 3F, but under 5F that alpha shrinks and an explicit positive profitability beta + positive investment beta pattern emerges. A tech-growth basket flips to negative profitability and investment betas, revealing "high-growth + aggressive investment" exposure. In short, FF5 is a sharper tool for diagnosing why a portfolio returned what it did.
+Is the 5-factor model always better than the 3-factor model?
Not "always". Adding factors almost always raises R², so a higher R² alone does not make it the better model. There is a cost, too — more coefficients estimated from the same number of months widen the error on each beta, and new factors that overlap with existing ones make interpretation harder. DIVA runs both models on the same window (up to 72 months) and the same factor sources, so run both on the same input and compare how the sign and significance of alpha move from 3F to 5F — that comparison pins down the portfolio's real character more precisely.
+Where does the Fama–French factor data come from? Is it free?
US-stock factors come free from the official data library run by Kenneth French at Dartmouth's Tuck School of Business (US factors for the 3-factor model, North American factors for the 5-factor model). They are usually published a month or two late, so the latest month may be missing from the regression. Korean stocks use DIVA's own KRW factors, computed from every KRX stock including delisted ones (from July 2016). DIVA calculates and adds new months separately, so recent months not yet added are left out of the Korean regression. Mixed KR / US portfolios are regressed on the two factor sets separately and combined by weight. Source links are in References at the bottom of the Fama–French model explanation page.