The BIS has issued two reports that assess the implications of unconventional monetary policies.

The report prepared by the Committee on the Global Financial System discusses

… a number of unconventional monetary policy tools (UMPTs). After a decade of experience with UMPTs the report takes stock of central banks’ experience and draws some lessons for the future.

The report focuses on four sets of tools: negative interest rate policies, new central bank lending operations, asset purchase programmes, and forward guidance. It offers a summary of central banks’ shared understanding of the efficacy of these tools across countries, as well as the way that they were sequenced and coordinated.

The report concludes that, on balance, UMPTs helped the central banks that used them address the circumstances presented by the crisis and the ensuing economic downturn. It identifies side effects, such as dis-incentives to private sector deleveraging and spillovers to other countries, but does not consider them sufficiently strong to reverse the benefits of UMPTs.

The report also discusses whether, and under what circumstances, these tools could be useful in the future. Central banks report that the tools have earned a place in the monetary policy toolbox, but they also highlight that their use should be accompanied by measures that mitigate their potential side-effects. They also highlight that under the circumstances when the tools can be helpful, they need to be used in decisively but in a context that includes a wider set of policies as to avoid overburdening the central bank.

The report prepared by a Markets Committee study group argues that

… some balance sheet-expanding policies were specifically aimed at improving market functioning, and that they delivered on this front. The potential for adverse side effects arose most clearly at a later stage, when asset purchase programmes were introduced to provide monetary stimulus at the effective lower bound for interest rates. But side effects rarely tightened financial conditions in markets to a point that would have undermined policy effectiveness.

That said, the report finds that some market malfunctioning did arise. In bond markets, adverse effects were mostly associated with asset scarcity, but any such effects were often temporary, in part due to mitigating policies. In money markets, market functioning issues (for example in interbank reserve trading) arose from the abundance of reserves. Yet, other wholesale money markets remained robust and central banks retained sufficient control over short-term rates, typically by introducing new tools. The report acknowledges that prolonged use of large balance sheet policies may have longer-term adverse effects on the market ecosystem, but these are hard to measure at this point.