# Efficient Market Hypothesis - [Efficient-market hypothesis | Wikipedia](https://en.wikipedia.org/wiki/Efficient-market_hypothesis) - Compare: [[market-efficiency|Market Efficiency]]. ## Levels of Market Efficiency - Weak Form Efficiency - The market fully reflects all historical price and volume information. - Technical analysis becomes ineffective, since past patterns can't predict future prices. - Fundamental analysis might still work to gain an advantage. - Semi-Strong Form Efficiency - The market reflects all publicly available information. - Both technical and fundamental analysis based on *public information* won't consistently generate excess returns. - Strong Form Efficiency - The market reflects all information, both public and private. - In strong form, how do we continue to profit? [[hft|High-Frequency Trading]].