A computer implemented method and system for automatically setting prices of financial products in a financial activity having a plurality of possible outcomes, includes receiving a first request from a participant terminal to purchase a financial product for one of the possible outcomes, i; and electronically computing a price for the requested financial product, in response to the first request, based at least in part on a first formula. Also included is a method for automatically updating the prices for all other outcomes, other than the outcome, i, based at least in part on a second formula. In one example, the financial products include contracts in a one-sided market of buyer participants where the outcomes are mutually exclusive and collectively exhaustive.