MFA Hedge Fund Glossary Definition – Due Diligence is what Fund Managers, lawyers and bankers do to learn about a company. In the M&A context, the buyer (and its lawyers and bankers) does Due Diligence so it can understand what it is buying. In Securities and Capital Markets transactions, the bankers and lawyers do Due Diligence in order to establish a Due Diligence Defense. In the bank loan market, bankers and lawyers do Due Diligence to make sure the deal makes sense. Diligence activities are broad and range from a review of relevant documents and Financial Statements to plant visits and interviews with management, outside accountants, counsel and customers and suppliers.