The degree to which existing emphirical evidence supports each of three forms of market efficiency hypothesis?

Empirical evidence supports the three forms of market efficiency—weak, semi-strong, and strong—differently. Weak form efficiency is supported by studies showing that past price movements do not predict future prices, as reflected in random walk theories. Semi-strong form efficiency has substantial backing, particularly from event studies demonstrating that stock prices adjust rapidly to new public information. However, strong form efficiency, which asserts that all information, public and private, is reflected in stock prices, has limited support, as insider trading consistently yields abnormal returns.