Emerging-market companies that took on more than $2 trillion of foreign borrowing since 2008 are vulnerable to an evaporation of funding at the first sign of trouble, according to the Bank for International Settlements (BIS).

Bond investors willing to lend generously when conditions are good can pull out in a crisis or when central banks tighten monetary policy, analysts led by Claudio Borio, head of the monetary and economic department, wrote in the BIS annual report. Emerging-market companies that lose access to external debt markets may then be forced to withdraw bank deposits, depriving domestic lenders of funding as well, they said.

Low interest rates and central bank stimulus in developed nations, combined with a retreat in global bank lending, have encouraged emerging-market borrowers to raise debt abroad, according to the Basel, Switzerland-based BIS, which hosts the Basel Committee on Banking Supervision that sets global capital standards. Demand for higher-yielding securities also helped suppress borrowing costs for riskier issuers.