Once your order has been filled, you may
think of the deal as done — except of course you'll
have to pay the bill if you've bought or be sure your account
is credited if you sold. But, in fact, much more happens in the
hours and days following execution than in the few minutes it
took you to place an order and for the transaction to occur.
Matching up
Comparison is the first step in that process. The details of the
transaction on the buy side are matched with the details on the
sell side: the name of the stock, the number of shares, and the
price. All that happens electronically — and close to instantaneously
— at the point of execution on whatever market the trade
was done.
Most of the time there is no problem. But
if an unmatched trade, which is one where the details supplied
by the firms don't match up, is reported, it's returned
to the firms for a second and even a third chance at resolving
the discrepancies.
