Other criticisms focused on TRIPS` failure to accelerate the flow of investment and technology to low-income countries, an advantage advanced by WTO members before the agreement was created. World Bank statements indicate that TRIPS has not been able to tangibly accelerate investment in low-income countries, although this has been done for middle-income countries.  The long periods of validity of patents under TRIPS have been examined to indicate that they excessively slow down market entry for generic drug substitutes and competition in the market. In particular, the illegality of preclinical studies or the filing of samples for approval until a patent expires has been held responsible for the growth of a few multinationals and not producers in developing countries. .