The simultaneous purchase and sale of assets that are potentially, but not necessarily, equivalent. For example, Firm A may make an offer to acquire Firm B by exchanging one share of its own stock for two shares of Firm B's stock. If the stock of Firm A is trading at $50 and the stock of Firm B is trading at $23, the risk arbitrager would buy shares in Firm B and sell short one-half this number of shares in Firm A. If the buyout offer is approved, the two stocks will exchange on a one-for-two basis, and the arbitrage position will be profitable. The risk is that the buyout will be unsuccessful, and the exchange of stock will not take place. Risk arbitrage is also used in situations involving reorganizations and tender offers. Also called equity arbitrage.