Hi, according to the notes, your account was exploiting a temporary pricing error for HBD on our site (these happen sometimes when we rely on a pricing source that has bad data, such as an exchange where deposits/withdrawals have been disabled, but trading is still allowed).

While this isn't illegal or anything, it's not "friendly" either, and ultimately such attacks mean we have to charge other customers more. So our policy is to just stop trading with accounts that do that.