Normally when the instruction is given to deal, the broker will transact ‘at best’ – buy at the lowest available price and sell at the highest. Another option is to set the broker a limit – set the maximum at which you are prepared to buy or a minimum price below which you are not prepared to sell. Usually such limits last for only 24 hours, though some brokers may be prepared to accept longer instructions of this sort.
Once the transaction is complete the broker sends a contract note detailing the deal and how much money is to change hands. It may take a little time to receive the share certificate but that is incidental since it is your presence on the share register that really determines ownership of the holding. The inconveniences can be circumvented by having the broker keep the holdings in a ‘nominee’ account or by having them registered in Crest, the Stock Exchange’s electronic registry of share holdings.