I have been looking into motif investing. They say they allow fractional shares. How do they clear fractional shares on their side of the trade? Let's say I buy 0.5share of AAPL, I don't know any other broker selling 0.5 shares, thus they should be buying full share. Unless they are finding another buyer who is willing to also buy 0.5 share at the same time as me, they should be taking on market exposure for the rest of fraction of the share that I am not paying for.