Every securities market transaction requires a buyer and seller with differing viewpoints. Differences between investors in their assessments of the intrinsic value and risk of securities allow markets to operate.
The securities markets provide an evolving consensus of the risk-adjusted value of particular securities. By understanding how the markets value securities, individual investors can chose more durable investment strategies.
Efficient market pricing or the theory that known information is reflected in current securities prices has become very widely accepted with the scientific investment community. The preponderance of evidence is that securities markets are efficient and tend to reflect available information.