The lunatics are running the asylum.
After an incessant flow of bad economic news from both the U.S. and abroad, investors decided that "bad news is good news" and they should bid up stock prices.
Saying "bad is good" is like saying "down is up" or "Hillary is telling the truth." It is so obviously contrary to the facts that you can't take it seriously.
And yet investors, in their infinite wisdom, decided that the economic news is so bad that the Federal Reserve (which itself doesn't know up from down) is not going to raise interest rates.
It's not clear how long this insanity will last, but I wouldn't be chasing stock prices here.