Fractional shares come with an additional risk, as pointed out by the terms and conditions
Fractional share investment carries some additional risks to whole share investment. Fractions of shares traded through our Service cannot be traded on trading venues and are illiquid and unrecognised outside our trading platform and Our US Broker. Fractional shareholdings bought through our Service cannot be transferred to another service provider and can only be liquidated through us.
In essence they are illiquid un-transferable and difficult to move in the event of an issue with the broker.
What I don’t know is if whole US shares pose the same risk?
e.g. if you but 0.5 of X and later 0.6 of X you have 1.1 of X. Is the 1 whole share considered a whole share and not subject to the same level of risk as fractional shares or does the nature of the US share dealing service mean that all US shares are treated as fractions?