# Adding more factors to Fama French Carhart 4 factor model

Does it make sense to add more factors such as Quality Minus Junk (QMJ) and Betting Against Beta (BAB) in the Fama-French-Carhart model? Also, if anyone can point me to an article it would be appreciated.

$$r=α+R_f+β_m(R_m−R_f)+β_s⋅SMB+β_v⋅HML+β_{umd}⋅UMD$$

Would add QMJ and BAB to the regression.

• Why do you want to do that? To better explain the cross-section of stock returns? Or to evaluate actively managed portfolios? In principle, you can add as many factors as you want to. – Kevin Jun 25 '20 at 0:02
• The idea would be to understand better stock returns. I am wondering if it will yield better coefficients and maybe evaluate actively managed portfolio having a low number of stocks – Circus_beta Jun 25 '20 at 1:43