what is weak efficiency

Weak efficiency refers to the idea that past price movements, volume, and earnings data do not affect a stock's price and cannot be used to predict its future direction. This concept is a part of the weak form efficiency hypothesis (EMH), which claims that the market is generally efficient and that stocks trade at the fairest value. According to weak form efficiency, it is impossible to find price patterns and take advantage of price movements because the randomness of stock prices makes it difficult to predict future price movements accurately.