Two of the four largest percentage declines for the Dow occurred on consecutive days — Oct. 28 and 29 in 1929. The market fell roughly 25 percent over those two days.The Dow reached an all-time high in September 1929 before the crash and did not return to its pre-crash high until 25 years later in November 1954. From its peak in September 1929, the Dow fell 89 percent, bottoming in the summer of 1932 at 41.22, the lowest closing level of the 20th century.The six largest single-day point declines for the Dow all occurred in the first six months of 2020 as investors grappled with the impact of the COVID-19 pandemic.The largest single-day point decline for the Dow occurred on March 16, 2020 when the index fell 2,997 points, or 12.9 percent.The largest single-day point decline for the S&P 500 also occurred on March 16, 2020, falling 324.9 points, or about 12 percent.