Economic historian Karl Polanyi has argued that where barter is widespread, and cash supplies limited, barter is aided by the use of credit, brokerage, and money as a unit of account (i.e. used to price items). All of these strategies are found in ancient economies including Ptolemaic Egypt. They are also the basis for more recent barter exchange systems.
Corporate barter focuses on larger transactions, which is different from a traditional, retail oriented barter exchange. Corporate barter exchanges typically use media and advertising as leverage for their larger transactions. It entails the use of a currency unit called a "trade-credit". The trade-credit must not only be known and guaranteed, but also be valued in an amount the media and advertising could have been purchased for had the "client" bought it themselves (contract to eliminate ambiguity and risk).
Debts in the wir currency, assigned the same value as the Swiss franc, could be paid with sales to any member of the bartering circle: if a baker needed to “purchase” eggs and flour from a farmer, the baker could pay off the debt by “selling” baked goods to another wir member. The farmer, in turn, could use his newly acquired credit to “buy” his own needed items or services. Despite a bank-led campaign to discredit the system, wir stuck. Today, it has more than 60,000 business participants and does the equivalent of about $4.4 billion in annual trade.