It is not necessary for a company to exploit its particular ownership-specific assets by investing directly in production facilities. It can export through the usual trade channels. Technology can also be licensed to companies in foreign countries in return for payment of fees or royalties. National and transnational companies use both of these alternatives. The main reason not to do so is the nature of the markets for materials, for intermediate goods or for finished products. In the world of the neoclassical economics, markets are assumed to operate perfectly. However, markets are imperfect, since the markets do not operate perfectly. The greater the imperfection the greater the incentive will be for a company to internalise market transactions, to perform the function of the market itself. The most obvious example of this is vertical integration where a company decides to control either its own sources of supply or the destination of its outputs. A great reason for a company to internalise markets is uncertainty. The greater the degree of uncertainty the greater the advantage will be for the company to control the transactions itself. Internalisation is especially likely to occur when there is transfer of knowledge. Another reason for internalisation is the price mechanism. In external markets prices are charged between buyers and sellers. In the internal market, on the other hand, prices are charged between related parties within the same organisation. The company itself sets the transfer prices of goods and services within the organizational boundaries. This leads to flexibility to help achieve the overall goals. There are limits in internalisation, too. There are particularly increased costs of communication and control of the separate organisational units.