Yes, if trading BCA results in a profit, either BC or CA has negative weight. Negative weight here just means you can sell a currency more than its cost basis,

Yes, if trading BCA results in a profit, either BC or CA has negative weight. Negative weight here just means you can sell a currency more than its cost basis, and or buy a currency for cheaper than its cost basis. Though with arbitrage, you typically want to find a cycle like BCAB so you have more of the initial currency you started off with.