In this paper, by the mechanism of securities transaction is meant a definite type of transaction which is formed by the following factors, what kind of trading contract is made, how it is executed and carried over, and what kind of credit is extended to it. In England the mechanism of the cash transaction developed into that of the time bargain, which has in turn become to the periodical transaction. In the view of the unit period of settlement, the mechanism of the daily settlement changed into that of the term settlement, too. In the United States of about 1790's, however, the dealing on credit was prevalent, and about the same days the time bargain was introduced from England. In 1817 the daily settlement which is generally said to be the regular way ploper to the United States arose and ever since it has continued to be in use, though it was, for three months in 1938, interrupted by the semi-weekly term settlement similar to the fortnightly settlement of the London Stock Exchange. The process of the above-mentioned historical development of various types in the trading mechanism indicates that, in the economic undeveloped stage, the type of transaction got much influence from the London type and that, with economic growth of the United States, it gave way to the regular way which still has the tendency to change further.