Central bank money inflated the markets for risky loans and the investment vehicles that buy many of them. Now, there are early signs of that driving force going into reverse.

In recent weeks, a growing share of new borrowers have had to lift interest rates on leveraged loans to win over investors. This might just be a touch of indigestion after several large deals to fund private-equity buyouts and takeovers, but some bankers think it is an early signal that liquidity is retreating from low-quality debt.

The trouble for borrowers isn’t rising debt costs today, but the risk that loans will be harder to refinance in future when investor money washes back to safer assets as yields improve. This matters because more than 40% of leveraged loans are typically used to refinance an existing loan. In the financial crisis, even some relatively healthy companies couldn’t refinance and had to reach deals with existing lenders to extend their debt.

Loans are popular right now because their yields adjust with interest rates, so they don’t lose money like fixed-rate bonds do during times of rising rates. The real problem lies in how investors who don’t normally buy loans will react to the end of quantitative easing, or central bank bond buying programs, which pushed them into risky loans in the first place.

As these programs unwind, more traditional fixed-income assets, such as government bonds and high-grade corporate debt, offer better yields. As bond yields recover to more normal levels and rate rises slow, investors won’t need to take risks on credit or complexity.