The developed world’s central banks are entering uncharted territory as they continue to experiment with negative interest rates, according to a report from the Bank for International Settlements, a consortium of central banks.

The central banks of the Eurozone, Switzerland, Sweden, Denmark and the Bank of Japan all currently have negative interest rates.

But despite the fact those central banks are penalizing lenders who hold money there—an effort to get money out and about, stimulating sluggish economies—inflation and economic growth remain stubbornly low in many areas, according to the Wall Street Journal.

As a result, BIS’ chief economist, Claudio Borio, says market participant confidence in central banks’ healing powers has—probably for the first time—been faltering.

Claudio also warned negative interest rates could have a disastrous impact on the business models of firms with long-term liabilities like banks, insurance companies and pension funds.

Even “as the BoJ and ECB signaled their willingness” to pursue easy money policies, “markets showed greater concerns about the unintended consequences of negative interest rates,” the BIS says in the report. [WSJ]