A list of stocks that are ineligible for trade by an investment bank's risk arbitrage division. The gray list is composed of firms working with the investment bank, often in matters of mergers and acquisitions. Taobiz explains Gray List While the risk arbitrage division is barred from trading within the gray list, the investment bank's block trading desk is eligible for such transactions. Because the gray list includes firms working closely with an investment bank, it is often confidential and kept close within the bank's trading divisions.