Efficient Market Hypothesis
The theory that asset prices already reflect all available information.
The efficient market hypothesis says asset prices already reflect all available information.
The efficient market hypothesis holds that prices instantly reflect all available information, so it is hard to consistently beat the market. In its strongest form it implies technical and fundamental edges are largely priced in. Most retail traders treat it as a useful caution rather than a strict rule, because markets are not perfectly efficient.
How It Works
- It implies beating the market is hard
- Markets are not perfectly efficient in practice
- It cautions against assuming easy edges
Trading Tips
Use it to question why a supposed edge works
Focus on edges that survive competition
Treat the theory as a warning, not a verdict
Efficient Market Hypothesis Example
Say a retail trader spends $2,000 on a black-box signal service promising 80% wins. Two years later the account trails a plain index fund after fees. The market absorbed whatever edge existed before the subscription started.
How Traders Use Efficient Market Hypothesis
Let EMH humble your system shopping: demand audited track records and out-of-sample proof. Assume edges decay, diversify methods, and keep costs low enough to survive being merely average.
Related Terms
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