The full arbitrage circle would be:
USD->HBD-> 3.5 days HIVE conversion ->USD

But there are not much liquidity for HBD outside the internal market, the BUSD-HBD pool on Cub might be the one place, but you cant do large swaps... say 10k plus.

The other option is to go trough the internal market and HIVE, and that would be:
USD->HIVE->HBD-3.5 days HIVE conversion ->USD

If the price of HIVE changes significantly during the conversions one can end up in a loss.