Either way, our actions will be guided by our remit of achieving low inflation with financial stability. Conclusion  The Covid crisis to date has demonstrated that QE and forward guidance around it have been effective in a particular situation. It emphasises that we remain in a world where the choice of tool to use is more important than it has been at times in the past. And there is more nuance and flexibility within tools – thus, while QE relies more on stock effects when used in normal times, in a case of extreme market dysfunction the flow effect of the liquidity channel may come to prominence. The MPC has moved on from that approach as market conditions have eased. In June we increased the stock of QE purchases, but at a slower pace. And in August we introduced forward guidance, stating that the Committee does not intend to tighten monetary policy until there is clear evidence that significant progress is being made in eliminating spare capacity and achieving the 2% inflation target sustainably. This important step is intended to ensure monetary conditions do not tighten prematurely when there are some initial signs of an economic recovery. We also made clear that our box does include other tools, including the possibility of negative rates. We have used private sector asset purchases through the corporate bond programme, longer-term liquidity provision to banks with targeted lending incentives, and direct purchasing of newly issued commercial paper to supplement market-based lending channels.
Standing back from the Covid crisis, and looking at the UK case, there indeed is some evidence that the impact of QE over the past decade has been largest at times of market dysfunction and illiquidity. Of course the available event studies are very few in number. But, if this result proves robust, it suggests that “going big and fast” with QE is particularly effective in these conditions. I should stress that while the liquidity channel of QE appears to have been particularly relevant in terms of impact at a time of market dysfunction, such as that observed in March, the different channels of QE impact are by no means mutually exclusive. It seems likely that each channel operates to at least some extent most of the time, with all of them affecting long-term interest rates and thus economic activity and inflation. But this need not suggest that all the channels are equally powerful and persistent in all states of the world. Implications for the future  What does this mean for central bank balance sheets looking forwards? Again, two points stand out, though I should emphasise their tentative nature. First, a balance sheet intervention aimed solely at market functioning is likely to be more temporary, in terms of the duration of its need to be in place. To be clear, the asset purchases announced by the MPC in March were a response to much more than just market functioning, in terms of the effects of Covid on the outlook for the economy and inflation.