When you purchase or sell stocks, you don't actually receive the stocks or the proceeds of a sale until the Settlement date. Up until September 5, this has been 3 business days after the trade date. Starting September 5, the Settlement date will come quicker. It will only be 2 business days after the trade date. Here is further information from the SEC about the change:
This change will also affect other things that are controlled by the settlement date. Two that you might run into in your investment club are:
1. Ex-dividend date - This will now be one day before the record date. In the past it was two days before. If you own a stock before the ex-dividend date, you get the dividend. If you buy it on or after that date, you don't.
2. Change in Lot Selection - If you sell multiple lots of a stock, you have until the settlement date to tell your broker which lots to sell. If you don't tell them otherwise, they will use the default lot selection method you have set up with them. If you don't want to use that for some reason, you'll have less time after a sale to make an adjustment.