If you're going to have friends ask you questions like:
- Has there ever been a period that the market has been down 5% or more in three consecutive months? or
- Is this the worst 91-day period in the past 107 years?
Then you are going to need some DOW data. And it had better be pretty long range to cover the Great Depression and other stock market excitement of the early 20th century. This text file is pretty good for simple purposes. Mind you, it covers only up to fall of 2007, but it's pretty easy to get this additional data from Yahoo.
Some things I did not know:
- The market was closed from late August 1914 through to December.
- The market as open only four days a week in 1968 or 1969 so that back office could catch up.
You have to make some decisions of how you will handle these cases.