This past summer my wife and I visited the beautiful Hawaiian island of Kauai and rented a cottage near the Napali coast. Twice a week the locals hold a farmers market next to the elementary school which we visited to buy fruits and vegetables for grilling with freshly caught Ono for dinner. This one local family sells delicious golden pineapples but you have to get to them early because they sell out fast. In the farmer's market, just like the stock market, the higher quality goods eventually command a premium over less desirable produce. Those pineapples were the Hanalei Bay equivalent of Apple stock selling at a high P/E ratio. Over time the demand for high quality produce like the pineapples should be uncorrelated with demand for lower quality fruit. For those who prefer common sense to statistics let me explain this macro-theory using a micro-metaphor.
Hypothetically let's imagine that Ben Bernanke shows up in the parking lot of the Hanalei Bay farmers market. Over a bullhorn he agrees to give away $1,000 to everyone in attendance on the condition they spend the money immediately. What will happen? The quality of the produce instantly becomes of secondary concern to simply realizing the full value of the hand out. Whether or not you are buying star fruit, pineapples, or bananas it is largely irrelevant because if you don't buy something you will lose out on the free subsidy. The demand for all produce will rise near equally as the correlations of fruit increase and the Hanalei Bay farmer's market ceases to function as a true marketplace.