CONSTRUCTION OF AN OPTIMAL PORTFOLIO USING THE SINGLE INDEX MODEL: AN EMPIRICAL STUDY OF PRE AND POST COVID 19. Journal of Pharmaceutical Negative Results, [S. l.], p. 406–417, 2023. Disponível em: https://www.pnrjournal.com/index.php/home/article/view/7991.. Acesso em: 11 jun. 2026.