Bernstein Global Research looked into how long it takes to regain losses if one remained fully invested in the market with a diversified portfolio. For the 12 month period starting July 1, 1931, with 67% decline the research showed it took 39 months to be made whole and recover the losses. For the 12 month period starting March 1, 2008, with a 43% decline the research shows it took 22 months to be made whole and recover the losses.