Transaction cost

In economics and related disciplines, a transaction cost is a cost incurred in making an economic exchange. For example, most people, when buying or selling a stock, must pay a commission to their broker; that commission is a transaction cost of doing the stock deal. Or consider buying a banana from a store; to purchase the banana, your costs will be not only the price of the banana itself, but also the energy and effort it requires to find out which of the various banana products you prefer, where to get them and at what price, the cost of traveling from your house to the store and back, the time waiting in line, and the effort of the paying itself; the costs above and beyond the cost of the banana are the transaction costs. When rationally evaluating a potential transaction, it is important to consider transaction costs that might prove significant.

A supplier may bid in a competitive environment with a customer to build a widget. However, to make the widget, the supplier will be required to build specialized machinery which cannot be easily redeployed to make other products. Once the contract is awarded to the supplier, the relationship between customer and supplier changes from a competitive environment to a monopoly/monopsony relationship. This means that the customer has greater leverage over the supplier such as when price cuts occur. To avoid these potential costs, "hostages" may be swapped to avoid this event. These hostages could include partial ownership in the widget factory; revenue sharing might be another way.

Car companies and their suppliers often fit into this category, with the car companies forcing price cuts on their suppliers. Defence suppliers and the military appear to have the opposite problem, with cost overruns occurring quite often.