Securities (i.e. financial instruments) and commodities are traded on an exchange using, making, and possibly changing the current market price.
In the OTC i.e., over the counter market, trades are based on contracts made directly between two parties, and not subject to the rules of an exchange.
[3] Spot markets can be either privately operated or controlled by industry organizations or government agencies.
They frequently attract speculators, since spot market prices are known to the public almost as soon as deals are transacted.
Examples of energy spot markets for natural gas in Europe are the Title Transfer Facility (TTF) in the Netherlands and the National Balancing Point (NBP) in the United Kingdom.