A market in which there are only potential buyers or potential sellers, but not both. That is, quotes for a one-way market only have a bid or an ask price. One-way markets are, by their nature, illiquid, and, on most exchanges, dealers and/or market makers exist to prevent them from forming. However, regulations sometimes require a one-way market to form, at least temporarily. For example, some countries forbid the resale of an IPO for a certain period of time.