CBOT sued over new grain price settings Two dozen pit traders at the Chicago Board of Trade are suing the exchange to block a new way of calculating grain prices, in the latest sign of friction over electronic futures dealing. CBOT, owned by exchange operator CME Group, on Monday combined quotes from computer screens with prices from its floor pits to calculate official closing prices for all grains and oilseeds. Before, corn and soyabeans were settled in the pits while rice, oats and the main wheat contracts were settled exclusively on screens. CME's move came after the US commodities regulator questioned the integrity of basing settlement prices in the pits alone. CBOT said it made the changes "as trading in our markets evolves. We believe the new settlement methodology accurately captures contract value across both the open outcry and electronic trading venues during the settlement period. Electronic trading now comprises more than 80 per cent of the volume in benchmark grain futures, up from percentages in the single-digits six years ago. The new settlement method is the latest reaction to this shift. The exchange recently lengthened its grain trading day to 21 hours from 17 as traders connect around the globe, a move that unnerved traditionalist grain merchants. In a civil lawsuit filed in a state court in Chicago, the pit traders said the change threatened their incomes and could spell the end of the open-outcry system of trading agricultural futures. The CME, however, wants the case to be decided in a US federal court instead and arguments on this issue were heard on Tuesday . In the lawsuit, the plaintiffs said their main livelihood was trading and filling orders in Chicago's open-outcry market, especially during the closing period when prices settle. Under the new settlement policy, most floor traders "will lose the vast majority of their business almost immediately and will have to close their operations forever," said the lawsuit. As a result of this rule change, hundreds of jobs supported by these traders, including their clerks, runners, information technology and other support staff will - and are being - eliminated. The traders also claimed the exchange did not honour a requirement to let exchange members, which include some plaintiffs, vote on the new policy before it took hold. "We believe CME and CBOT did not follow their own rules," said George Sang, an attorney for the plaintiffs. CME declined to comment specifically on the litigation.