In an efficient market, the price of a security will:
be slow to react for the first few hours after new information is released allowing time for that information to be reviewed and analyzed.
react to new information over a two-day period after which time no further price adjustments related to that information will occur.
always rise immediately upon the release of new information with no further price adjustments related to that information.
react immediately to any new information that affects the value of the issuing firm.
rise sharply when new information is first released and then decline to a new stable level by the following day.