What does the Efficient Market Hypothesis imply?

The Efficient Market Hypothesis (EMH) is a theory in financial economics that states that asset prices fully reflect all available information. Here's what it implies:

1. Prices are fair: If the market is efficient, the prices of securities in the market are fair. They reflect the true intrinsic value of the security. This is because all known information about the security is already incorporated into the price.

2. No room for "beating the market": If all information is already incorporated into the prices of securities, then no investor has an advantage over another in predicting. This means it's impossible to consistently achieve higher than average returns on investments, unless through luck or inside information.

3. Random Walk Theory: The EMH implies that future price movements are determined entirely by information not yet known and thus, cannot be predicted. This is often referred to as the "random walk theory."

4. Rational Investors: The EMH assumes that investors are rational and react quickly to new information. Therefore, the market is always in equilibrium.

5. Three forms of EMH: Depending on how much information is considered to be fully reflected in the prices, there are three forms of EMH: weak, semi-strong, and strong. The weak form suggests that past price information is reflected, the semi-strong form suggests that all public information is reflected, and the strong form suggests that all public and private information is reflected.

6. Implications for Investment Strategies: If the EMH holds true, then it would imply that more speculative and active trading strategies may not yield consistently higher returns than a passive strategy, such as investing in a diversified portfolio of securities and holding them over a long period.