海外之声 | 作为货币政策工具的央行资产负债表

导读

在过去十年中，大多数中央银行的资产负债表一直在持续大规模扩张。这是为了支持货币政策和金融稳定目标。

全球金融危机显示，银行之前持有的优质流动资产不足，部分原因是当时的审慎监管制度不足。自那时以来，监管和银行管理风险的方式发生了变化，导致对央行储备的需求显著增加，这是银行高质量流动资产存量的很大一部分。其次，在过去的十年中，货币政策也发生了重大变化，转向使用中央银行资产负债表作为通过购买资产（通常是政府债务）提供货币刺激的工具。十年前，我们有理由认为，增加中央银行资产负债表的货币政策需求将是短期的，而金融稳定需求将是永久性的。这种区别仍然存在，但是低均衡利率的结构性驱动因素表明，将央行资产负债表用于货币政策的期限将比预期的更长。

而在近期，央行资产负债表扩张的金融稳定性和货币政策驱动力再次交织在一起。中央银行面临着初期的金融稳定冲击，同时还需要采取货币政策来应对规模空前的经济下滑。但是，金融稳定应急与之前的此类事件有所不同。问题不仅仅起源于银行系统，还起源于非银行部门。中央银行激活了其传统工具，通过逆回购操作向银行注入流动性，这些工具在稳定条件方面发挥了重要作用。但是它们不能以足够快的或足够的规模为非银行提供流动资金。这还需要进行大规模且激进的资产购买操作。

新冠危机迫使各国央行采取行动，这是金融危机后对全世界的首次重大考验。货币政策必须应对前所未有的冲击。对于许多央行而言，迄今为止的主要工具是以前所未有的规模和购买速度推动进一步的量化宽松。这不可避免地引发了关于量化宽松政策究竟如何运作、其有效性是否取决于经济和金融体系状况的问题。

迄今为止的新冠危机表明，量化宽松和围绕它的前瞻性指导在特定情况下是有效的。它强调在当今世界里，使用工具的选择或许比过去更为重要。而在工具内还有更多细微差别和灵活性。因此，尽管在正常时间使用量化宽松时更多地依赖库存效应，但在极端市场失灵的情况下，流动效应可能会更为突出。

作者 | 安德鲁·贝利（Andrew Bailey），英格兰银行行长

英文原文如下：

The central bank balance sheet as a policy tool: past, present and future

Speech given by Andrew Bailey, Governor of the Bank of England, at Jackson Hole Economic Policy Symposium, 28 August 2020

Introduction

It’s a great pleasure to be participating in the virtual Jackson Hole conference. Well done to the Kansas City Fed for keeping up the tradition – albeit we have to imagine the beauty of Jackson Hole is around us.

A tradition of the Jackson Hole conference is to encourage us to look forwards. This time is not only an opportunity to do just that, but in doing so to apply the lessons of the last few months, as well as the last decade or so since the financial crisis of 2007-09. I am going to do that through the lens mainly of monetary policy, but bringing in financial stability where relevant, with a particular focus on central bank balance sheets. My remarks are a summary of a paper being released today. It isn’t a review of the record of monetary policy or the framework of policy, but it does cover a good deal of recent evidence and experience. The paper, and my remarks today, focus on the UK case, drawing on lessons from international experience.

Drivers of central bank balance sheets since the Global Financial Crisis

I will start with some brief scene setting points – apologies that they are pretty obvious ones, but they are important. There has been a large and sustained expansion of most central bank balance sheets in the past decade. This has come about in support of both monetary policy and financial stability objectives. These respective drivers of balance sheet growth are closely intertwined – never more so than in the response to the Covid crisis – but distinguishing the causes and consequences is important nonetheless.Starting with financial stability, the Global Financial Crisis revealed banks had previously held insufficient high quality liquid assets, in part due to the inadequacy of the prudential regulation regime at the time. The changes since then, in regulation and in banks’ approach to managing risk, have resulted in a significant increase in the demand for central bank reserves, a large part of banks’ stock of high quality liquid assets. Thus, the level of reserves required by the banking systems in the major economies is persistently higher, though it is not straightforward to determine exactly how much higher. That depends on a number of factors that can change over time.Second, monetary policy has also undergone a major shift over the past decade, towards using central bank balance sheets as a tool to provide monetary stimulus, through the purchase of assets, usually government debt.These two reasons for increasing the size of central bank balance sheets coincided in time – i.e. the post- crisis response of regulation coincided with the greater use of quantitative easing. But it is nonetheless helpful to separate them analytically. A decade ago there would have been reason to think that the monetary policy need for increased central bank balance sheets would be shorter term, while the financial stability demand would be permanent. That distinction still stands, but the structural drivers of low equilibrium interest rates suggest the use of central bank balance sheets for monetary policy will be more long-lived than had been anticipated.

Expansion of central bank balance sheets in response to Covid

Turning to the more recent period, the financial stability and monetary policy drivers of central bank balance sheet expansion were again deeply intertwined. Central banks faced an incipient financial stability shock together with a need for monetary policy to respond to an unprecedented – in scale and speed – economic downturn.

But the financial stability emergency differed from previous such events. The problem originated not primarily in the banking system, but in the non-bank sector – among funds, traders and corporates themselves. Central banks activated their traditional tools to inject liquidity into the banks via repo operations, and these played an important part in stabilising conditions. But they were not sufficient to get liquidity to non-banks quickly enough, or in sufficient scale. That also required large and aggressive asset purchase operations, what we call in the paper “go Big” and “go Fast”. I am not going to say more on this, save that it raises very important points about market structures, the extent of self-insurance against liquidity shocks by non-banks, and the nature of central bank interventions. This is the subject of a review currently being undertaken by the Financial Stability Board.The Covid crisis called on central banks to act in what has been the first big test of the post financial crisis world. Monetary policy has had to respond to an unprecedented shock. For many central banks, the main tool to date has been further Quantitative Easing, in unprecedented scale and pace of purchases. This has inevitably rekindled questions about exactly how QE works and whether its effectiveness is conditional on the state of the economy and the financial system – to what extent is its effectiveness state contingent? Moreover, looking across monetary policy and financial stability, it has re-emphasised the importance of central bank balance sheets as a direct tool of policy intervention, rather than primarily a passive by-product of the activity of setting the price of money and meeting the demand for reserves to satisfy the liquidity needs of the banking system.So what is our latest thinking on the effects of QE and how it works? Viewed from the depth of the Covid crisis, QE worked effectively. Measuring this effect precisely is of course hard, since we cannot easily identify what the counterfactual would have been in the absence of QE. But QE clearly acted to break a dangerous risk of transmission from severe market stress to the macro-economy, by avoiding a sharp tightening in financial conditions and thus an increase in effective interest rates.QE is normally thought to work through a number of channels: including signalling of future central bank intentions and thus interest rates; so called ‘portfolio balance’ effects (i.e. by changing the composition of assets held by the private sector); and improving impaired market liquidity.The Monetary Policy Committee’s decision on QE in March differed somewhat from previous rounds of purchases. A larger amount of purchases, £200bn, was announced as this was judged as necessary to support economic activity and ensure a sustainable return of inflation to target. And the purchases were to “be completed as soon as is operationally possible” to address the emerging financial market dysfunction.In the paper we draw two lessons from the experience. First, it reminds us that the effect of QE can be state contingent. Consistent with that, second, the pace of QE purchases may be more important during a period of market dysfunction associated with a widespread shock to liquidity demand. Indeed, when the MPC voted to expand QE further in June, in more normal market conditions, the pace of purchases was reduced.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. Second, if the effects of QE are more powerful in crisis states of the world, we may need to ensure that we have enough headroom in the future to repeat it. The determinants of QE unwind may therefore be more subtle than previously thought, and the Covid crisis offers a new lens through which to assess its role.This leads to what may be regarded as the most speculative of the conclusions, but it strikes me as important as we look to the decade ahead. It follows from the state contingent nature of the effects of QE, and the argument for going “big and fast” in such situations, that the central bank balance sheet may have more of a counter-cyclical role and function than the evidence of the last decade alone would suggest, at least in certain circumstances. We need to work through what lessons this may have for the appropriate future path of central bank balance sheets, including the pace and timing of any future unwind of asset purchases. But one conclusion is that it could be preferable, and consistent with setting monetary conditions consistent with the inflation target, to seek to ensure there is sufficient headroom for more potent expansion in central bank balance sheets when needed in the future – to “go big” and “go fast” decisively.That begs questions about when does the need for headroom become an issue? What are the limits? One way of looking at these questions is in terms of the stock of assets available for purchase. There is currently a large outstanding stock of government bonds which could be purchased. And if the state contingent effects of QE are driven by the need for holders of safe assets to exchange them for deposits, then it must always be possible for the central bank to purchase more assets. In other words, the central bank would need to own a high proportion of safe assets for that to become a constraint. But if negative shocks continue to arrive from time to time before any reversal of the stock of asset purchases takes place, and hence the stock owned by the central bank continues to rise, the odds of this situation arising go up. This effect may become more likely if the equilibrium real interest rate remains low for a prolongedperiod.Expanding the range of assets purchased is another way for central banks to create more headroom. The Covid crisis has seen a further broadening of the range of assets that central banks stand ready to purchase. In part, this has reflected another objective of central banks and governments, given the scale of the crisis and its economic effects, namely to direct and target funds to the corporate sector, and thus supplement the more normal role of banks and financial markets. But it also reflected a need to act on a broad front in terms of ensuring liquidity gets to the places where it is needed. Where that requires larger purchases of a broader array of assets, it inevitably raises risk management questions for central banks.So, I think the Covid crisis has demonstrated the need to ensure central banks have as many tools as possible in their box, of which expanded purchases of private sector assets is one, but given the issues it raises I would emphasise state contingency here in terms of when some tools may be more appropriate or necessary, given the severity or particular nature of the circumstances at the time. The MPC has considered its prospective approach to QE unwind in recent years, and in June 2018 set out that the balance sheet would be unwound at a gradual and predictable pace, allowing reserves to fall back to a level demanded by banks through their participation in regular repo operations, and once the Bank Rate had risen to around 1.5%, thus creating more headroom for the future use of Bank Rate both up and down. The MPC keeps this approach under review, though I should make clear that it does not seem like an imminent issue in current conditions. But we are looking at the next decade at this conference, so who knows what will happen. We should keep the options to use all our tools as open as possible, so I would conclude that the appropriate policy mix going forwards over a decade may be more nuanced than previously thought. 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. We are not out of firepower by any means, and to be honest it looks from today’s vantage point that we were too cautious about our remaining firepower pre-Covid. But, hindsight is a wonderful thing when you have it. In the decade ahead, I think we need to take on board the message the Covid crisis has reiterated, namely that our tools may be state contingent in their effects. And with that in mind, let’s not ignore the need to manage central bank balance sheets to enable such state contingency to take effect. There are times when we need to go big and go fast.Thank you.

编译  何映儒

编辑  易景阳

来源  BIS

责编  李锦璇、蒋旭

监制  安然、魏唯

点击查看近期热文

欢迎加入群聊

为了增进与粉丝们的互动，IMI财经观察建立了微信交流群，欢迎大家参与。

入群方法：加群主为微信好友（微信号：imi605）,添加时备注个人姓名（实名认证）、单位、职务等信息，经群主审核后，即可被拉进群。

欢迎读者朋友多多留言与我们交流互动，留言可换奖品：每月累积留言点赞数最多的读者将得到我们寄送的最新研究成果一份。

关于我们

中国人民大学国际货币研究所（IMI）成立于2009年12月20日，是专注于货币金融理论、政策与战略研究的非营利性学术研究机构和新型专业智库。研究所聘请了来自国内外科研院所、政府部门或金融机构的90余位著名专家学者担任顾问委员、学术委员和国际委员，80余位中青年专家担任研究员。

研究所长期聚焦国际金融、货币银行、宏观经济、金融监管、金融科技、地方金融等领域，定期举办国际货币论坛、货币金融（青年）圆桌会议、大金融思想沙龙、麦金农大讲坛、陶湘国际金融讲堂、IMF经济展望报告发布会、金融科技公开课等高层次系列论坛或讲座，形成了《人民币国际化报告》《天府金融指数报告》《金融机构国际化报告》《宏观经济月度分析报告》等一大批具有重要理论和政策影响力的学术成果。

2018年，研究所荣获中国人民大学优秀院属研究机构奖，在182家参评机构中排名第一；在《智库大数据报告（2018）》中获评A等级，在参评的1065个中国智库中排名前5%。

国际货币网：http://www.imi.ruc.edu.cn

微信号：IMI财经观察

（点击识别下方二维码关注我们）

理事单位申请、

学术研究和会议合作

联系方式:  

010-62516755 

[e-mail]

只分享最有价值的财经视点

We only share the most valuable financial insights.