How are final stock prices arrived at?
Its really quite simple, the stock price you're seeing is actually the last trade that took place, the different bids are tails of the suppliers and demanders - their maximal or minimal bids

In everyday trade the simultaneous bids arr very close, and the deals are happening all the time, more or less bids in a certain direction can point out market expectations, but in a range of minutes
This applies to high volume markets, of course