O

One-way Market
A market which only can quote a firm price on either the bid or the ask side. This can be caused by temporary market inefficiencies or by regulatory controls, as can be found in some foreign countries. A one-way market also can be created when there are only buyers, or only sellers, interested in a particular asset or security at a specific point in time. A slang term to describe a market that is moving strongly in one direction with little resistance.

Option
A financial derivative which represents a contract sold by one party (option writer) to another party (option holder). The contract offers the buyer the right, but not the obligation, to buy (call) or sell (put) a security or other financial asset at an agreed-upon price (the strike price) during a certain period of time or on a specific date (excercise date).