Service providers going broke has no effect on your holdings. Over the years several brokerage houses have gone under (some in spectacular fashion ie FXCM a few years ago). As long as your account/holdings aren’t in the negative, everything you own still belongs to you and is fully withdrawable. Generally when a broker goes under it means their business is no longer solvent and they can’t provide the service to you. It has no bearing on the value of your assets or holdings.
