Japan’s Economic White Paper of 1992 described the ties between parent companies and their parts suppliers. These relationships, it said, tend to be long-term and continuous, unlike ordinary spot market trading. Out of cooperation, a relationship of trust is thought to emerge that does not rest on an explicit contract. Shareholdings and the dispatch of directors reinforce the ties.
The paper called the keiretsu system very efficient for the buyers and sellers involved. It also noted its costs, such as the burden on subcontractors.