To sell your fractional shares, round down to the next whole number. So if you had 100.45 shares of XYZ, just type in 100 shares and the .45 will also get sold, on the condition that you only have 100.45 shares.To sell fractional shares you have to be closing down your entire position in a stock at that time.or example, if you have 500.45 shares, and you type in 100 for shares to sell, you will not sell the fractional shares, in that case, for the fractional shares to be sold you would need to enter 500 in the sell amount. mcc. Posted by mcc on January 26, 2009 (11:10PM).