I am more than agree with the former arguments. But I want to stress the infulunce of the entity economy, or the macro economy. They play a key role in the process that determine the stocks price. Just as mentioned before, the employ rate, the consumer's confidence, and even the government's policy. Monetary policy, such as QE, could have caused a lot of so called "hot money" pour into the stock market, which can greatly rise the price.