There is no mystery. It's the Fed. And frankly, it's disingenuous for Schiller to pretend that he doesn't know why.

Quantitative easing is working exactly as the Fed had hoped. It's causing bond prices to be sky high, mortgage interest rates to be as low as they've ever been, the stock market to be sky high, house prices to be sky high, etc.

Now, what happens when the Fed takes away its QE? No one knows for sure, but many speculate that all these bubbles will burst, because they are all artificially generated.

Personally, I am going to be taking all my money out of the stock market some time next year, and wait for the crash in October 2015. Crashes usually happen around that time, and then hopefully the economy survives this second recession. Until then, the sky's the limit in terms of where Wall Street is going to push the stock market.