Prior to an acquisition of a stock corporation the purchasers often perform a due diligence at the target company. The due diligence is the examination of the company and can cover the legal, commercial, environmental, financial and fiscal matters of the company. Under US law it is the purchaser's duty to examine a company accurately since the risk of any deficiencies is on him. German law, in contrast, does not require the purchaser to examine the company he purchases. According to § 442 (1) sentence 2 of the German Civil Code (Bürgerliches Gesetzbuch – BGB) the buyer does not have rights with respect to a defect, if he is unaware of this defect as a result of gross negligence on his part. While for some years now, the performance of due diligence prior to purchasing a company has become quite customary in Germany, German law does not yet require the person wanting to purchase a company to perform a due diligence.