What is residual stock?
A residual stock is one that does not settle through CREST. It is called 'residual' because the vast majority of trades are settled through CREST.
If you call to trade in a residual stock the trade would be placed in the same way as a CREST stock. No special restrictions apply. However, residual stocks are subject to a longer settlement period – usually 10 business days following the date of the trade.