Risk arbitrage
（重定向自Merger arbitrage）
Risk arbitrage, or merger arbitrage, is an investment or trading strategy often associated with hedge funds.
Two principal types of merger are possible: a cash merger, and a stock merger. In a cash merger, an acquirer proposes to purchase the shares of the target for a certain price in cash. Until the acquisition is completed, the stock of the target typically trades below the purchase price. An arbitrageur buys the stock of the target and makes a gain if the acquirer ultimately buys the stock.