patrick.net

Printing money would increase supply thus contributing to inflation and making companies more valuable in fiat dollars. This would help the argument that the stock market is fairly priced and should go up from here.
I'm unsure of the direction, myself. I'm buying individual stocks that I believe in and have researched carefully rather than bet the entire market to go up. That seems to be much more of a crap shoot carny game to me.

Quigley says

Printing money would increase supply thus contributing to inflation and making companies more valuable in fiat dollars.

Artificially. Fed buys bonds with what amounts to Monopoly money, which allows for money in the stock market. The dollar would devalue and the market would crash again.

These are two issues.
The stock market is not so much of a bubble, as a consensus prediction on whether a company's profits will grow or not.
Some recent information about increased growth of sales and profits of Apple, Caterpillar, McDonalds, Walmart, etc caused their stocks to be bid back up in this auction.
The low interest rates means that stocks with dividends are more attractive than money in the bank. The old saying that you should put your money into stocks at times like these is : "Don't fight the Fed."