risk arbitrage

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The simultaneous purchase and sale of assets that are potentially but not necessarily equivalent in order to exploit a discrepancy in price.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun arbitrage involving risk; as in the simultaneous purchase of stock in a target company and sale of stock in its potential acquirer; if the takeover fails the arbitrageur may lose a great deal of money