You have not mentioned which market you refer to so I have found
information on three markets. All indicate that it is not possible to
predict the starting price as many over-night factors will affect the
This is information on the London Stock Exchange. Start with this
article by way of introduction.
?On SETS and SETSmm nothing happens between the end of the closing
auction and the start of the following day's opening auction.
Obviously any number of factors (news/announcements/relationship of
buyers to sellers etc) between the market close and the market open
can, and do, impact the opening price.?
This is information from the LSE on SETS and SETSmm.
SETSmm with Interactive demonstration for SETSmm
Graphic on SETSmm
These sites deal with the US market.
Shares - Glossary
?Open - A security's price when the market opens for business. The
opening price is not necessarily the same as the previous day's close
because of after hours news releases, foreign exchange trading,
changes in analyst opinions, and changes in buy and sell orders. On
the New York Stock Exchange and the American Stock Exchange a
specialist selects the opening price that clears the most orders. On
the Nasdaq, firms post bid and ask prices on computer to determine the
?How can my stock's price change after hours, and what effect does
this have on me as an investor? Can I sell the stock at the
What is after-hours trading? Am I able to trade at this time?
Morgan Stanley - Glossary
?Opening - The first transaction in each security or commodity when
trading begins for the day occurs at what's known as its opening, or
opening price. Sometimes the opening price on one day is the same as
the closing price the night before. But that's not always the case,
especially with stocks or contracts that are actively traded in the
This is how the Australian Market deals with the opening price.
I hope this answers your question. If it does not, or the answer is
unclear, then please ask for clarification of this research before
rating the answer. I shall respond to the clarification request as
soon as I receive it.
"opening price" share "after-hours"
"opening price" share