That's a damn good question and I have been wondering about that myself. I have been trying to compare many of the averages and even a few stocks to the $USD (as a ratio like this)
It is interesting sometimes, but I haven't gotten a whole lot of useful data from it. If you look at that chart on a weekly basis, the ratio is about as high as it has ever been.
The last time the markets got out of hand vs. the $USD was probably 1987. That lead to the crash, but these charts don't provide much useful info to compare to that time period.
Register for free to join our community of investors and share your ideas. You will also get access to streaming quotes, interactive charts, trades, portfolio, live options flow and more tools.