on various reference prices with economic corrections built in. Contracts traditionally specify a base price, such as the uranium spot price, and rules for escalation. In base-escalated contracts, the buyer and seller agree on a base price that escalates over time on the basis of an agreed-upon formula, which may take economic indices, such as GDP or inflation factors, into consideration. A spot market contract usually consists of just one delivery and is typically priced at or near the published spot market price at the time of purchase. However 85% of all uranium has been sold under long-term, multi-year contracts with deliveries starting one to three years after the contract is made. Long-term contract terms range from two to 10 years, but typically run three to five years, with the first delivery occurring within 24 months of contract award. They may also include a clause that allows the buyer to vary the size of each delivery within prescribed limits. For example, delivery quantities may vary from the prescribed annual volume by plus or minus 15%. One of the peculiarities of the nuclear fuel cycle is the way in which utilities with nuclear power plants buy their fuel. Instead of buying fuel bundles from the fabricator, the usual approach is to purchase uranium in all of these intermediate forms. Typically, a fuel buyer from power utilities will contract separately with suppliers at each step of the process. Sometimes, the fuel buyer may purchase enriched uranium product, the end product of the first three stages, and contract separately for fabrication, the fourth step to eventually obtain the fuel in a form that can be loaded into the reactor. The utilities believe—rightly or wrongly—that these options offers them the best price and service. They will typically retain two or three suppliers for each stage of the fuel cycle, who compete for their business by tender. Sellers consist of suppliers in each of the four stages as well as brokers and traders. There are fewer than 100 companies that buy and sell uranium in the western world. In addition to being sold in different forms, uranium markets are differentiated by geography. The global trading of uranium has evolved into two distinct marketplaces shaped by historical and political forces. The first, the western world marketplace comprises the Americas, Western Europe and Australia. A separate marketplace comprises countries within the former Soviet Union, or the Commonwealth