Thursday marked the second largest single day drop in the Dow Jones Industrial Average since the Great Depression. However, the rebound on Friday was similarly robust. The shock was violent enough to encourage regulators to push for updated computer models at the nations leading stock exchanges. The viz below details every drop greater than 5% since 1928- check it out!
The "valley" that you can see in the top graph is an alarming one. Essentially, there were only three major drops (>5% drop from previous days close) from 1950-1979. There have been 43 since 1980. Although this is nowhere near the number for the 1930's, it clearly shows a return to more volatile markets.
Staggered interactivity: It is natural for the eye to move from top to bottom while reading or viewing a viz. This viz takes advantage of that tendency by using the top view as a filter.