Global debt may be under-reported by around $13 trillion because traditional accounting practices exclude foreign exchange derivatives. Bank for International Settlements (BIS) researchers said it was hard to assess the risk this missing debt poses, but that the main worry was a liquidity crunch like the one that seized FX swap and forwards markets during the financial crisis. The $13 trillion exposure exceeds the on-balance-sheet debt of $10.7 trillion that was owed by firms and governments outside the United States at end-March. The fact these FX derivatives do not appear on balance sheets means little is known about where the debt lies. According to Claudio Borio, head of the BIS's monetary and economic department, the debt remains obscured from view.