It doesn't seem to me the breaking point of the stock market is what we have to worry about. I see the problem as being the breaking point of the people.
Let me try and explain.
I'm seeing the stock marked as only a reflection of the value of the currency. When they double the amount of money in the system the stock market adjust accordingly by changing the asking and selling price.
Take a look at this chart Robert Sahr came up with based on the Consumer Price Index showing the devaluation of the dollar.
Robert Sahr Dollar Devaluation
(Image by Robert Sahr Oregon State University) Permission Details DMCA
Even before the central banking system we have now we were able to introduce counterfeit money into the system and throw the value of the dollar off. See how we did it in times of war numerous times?
Now look at a long term look at the Dow Jones Industrial average.
Notice how its baseline of about 500 matches Robert Sahr's chart baseline of about $5.00. Then they both top out at about 13000 and $130.00 respectively. I thinking the DOW is adjusting to keep its value current with the devaluation of the dollar.