Semi-strong efficiency

Under semi-strong efficiency, prices adjust to public information such as results announcements, economic releases and publicly known strategy. Investors should not consistently earn abnormal risk-adjusted returns after costs merely by processing information already publicly incorporated. This includes weak-form information but does not require private information to be reflected. It does not prevent price jumps when genuinely new public news arrives or guarantee that a particular valuation is exact. Market access, disclosure quality and trading frictions can affect how closely actual markets approach the model.