The ongoing class action is the only reason that an entity would be able to acquire shares over the past 2 years without filing a form 13. As poster R239244094042 pointed out, a position can be kept if filed for confidential treatment. I have legal friends who have confirmed it's quite possible that an ongoing class action would be sufficient for such treatment. However, if there is an ongoing acquisition of shares, a quarterly update must be filed showing an ongoing intent to acquire shares. Interestingly enough, at least once every quarter for the last 2 years we've had days of large volume for no apparent reason. Ebola was the latest. I expect there will be one in January also.