Which is kind of crazy: It looks like their default margin is 100% of your cash balance. It would be much more transparent to be opt-in & say "Hey, you deposit

Which is kind of crazy: It looks like their default margin is 100% of your cash balance. It would be much more transparent to be opt-in & say "Hey, you deposited $1k. If you want, we're willing to loan you an additional $1k." I think more people might refrain from margin trading if it was presented that way. But it would reduce trading volume, and therefore a major revenue source in the form of trading data they sell to market makers, so of course they don't do that. As it stand though, to my outsider's eyes it makes their theoretical liabilities twice their collateral. Normally that's probably fine, gains & losses on large volumes of divers stockes will even out. But in unique circumstances (um, right now) the collapse of a single stock (or worse, a highly correlated asset class) puts them on the hook for an amount equal to their customers' losses. Considering their retail clientele, it's probably fair to assume that many of their customers can't (or won't) cover those loses by depositing more cash... hence the suicide a while back.