The close of business on the record date is when they check the...

The close of business on the record date is when they check the records of the share registrar to see who is entitled to participate in the offer. Because there is a delay between buy and sell orders being executed by the broker (we have a T+2 system) and the records being updated on settlement, the important date for investors is the ex-date. If you buy shares on or after the ex date, they will not be processed by close of business on the record date and you will miss out on the offer. If you buy shares prior to the close of business on the day before the ex-date, T+2 will ensure that the purchase is recorded on the books by the close of business on the record date, so you can participate.

Also, you can sell shares on or after the ex-date as the sale will not be processed by the close of business on the record date, so you will still be able to participate. For this reason, you may see big sells on and after the ex-date as people no longer need to hold the shares to participate.