Anticipated trade
One agent makes a deal with another to buy a certain amount of an ’underlying’ security on a specified future date at a certain ’strike’ price. To satisfy this deal, the seller is obliged to buy the security - if he does not already hold it - on or before the due-date.
Motivation
The seller is betting that the market price of the security on or before the due-date will be lower than the set price; and the buyer is betting that the market price will exceed the set-price on or after the due-date. So, both stand to make a profit according to their beliefs.
Effect on evaluation
If one ignores market jitters, the beliefs of the buyer and seller are mildly contradictory, in that believes that there will be a fall in the price of the security, whereas they buyer believes that there will be a rise in the price of the security.
These publicly stated beliefs have an effect on the evaluation of securities - speculation about the future can cause currency or commodity prices to rise even during the present time.