profitability strategy This refers to the industrial handicraft industry from the feudal society to the early stage of capitalism. In the 16th century to the 17th century, some western countries of the feudal social system to the system of capitalism, capitalist primitive accumulation is accelerated, deprived of farmers' land on a large scale, make cottage industry collapse, sharply to capitalism works system transformation. Industrial handicraft industry is the embryonic form of enterprise. Then the interest rate theory of the loan is the interest rate theory of neoclassical school, which is proposed to correct Keynes's theory of "liquidity preference". In some ways, the theory of interest rate can be regarded as a synthesis of classical interest rate theory and Keynesian theory. The earliest efforts were made in the areas of canning, Alexandria, munez and spaurous. This two days of U.S. stocks in the capital market, there was a dark horse, the named Longfin company, in just two days, rose more than 2000%, and due to rise too fast, multiple trigger exchange circuit breakers. It is understood that the company is mainly engaged in the use of artificial intelligence technology to provide financial services. Longfin (NASDAQ: LFIN), which was founded in February, has been trading on the NASDAQ stock exchange since last week at $5 a share, a very young start-up.