mpoda, page-27

What people need to understand is that some brokers or non-broker participants on CHESS use different systems for their clients.

Those client systems are sometimes programmed to update based upon "ex dates" as opposed to relying on the registry or CHESS system.

It really does not matter, because anyone can buy or sell, so long as they are prepared to pick up a telephone and speak for 1 minute. It is far better than the alternative which would involve going into a trading halt for a week.