A form t means pre-market or after hours trade. As for the reason... this could be your answer :-D
"For the individual as well as the institutional investor, Form T trading does present a few important advantages. If the investor happens to find out something that may have an effect on the price of a stock after hours, they have the convenience of acting on that information immediately. Otherwise, it would be necessary to wait until the markets open again, by which time the information will have reached many more investors, making it harder to profit from the situation. Form T trading also makes buying and selling U.S. stocks more convenient for foreign investors who operate outside the usual hours of trading in the U.S."
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