Discussion 500 words or more

Discuss how efficient the U.S. financial markets are in pricing financial securities. 

(Consider such questions as, "Are security prices reliable?", "What factors promote or reduce pricing efficiency?", and "How can we account for significant pricing fluctuations?")

Your response should be a minimum of 500, clearly written, with sources cited, and spelling and grammar checked before posting. 

Although you may refer to the ideas of others, I'm primarily interested in your own opinion, so you should avoid simply relying upon outside sources.