没有合适的资源?快使用搜索试试~ 我知道了~
CoVaR方法介绍
需积分: 50 62 下载量 168 浏览量
2019-01-18
17:46:54
上传
评论 8
收藏 325KB PDF 举报
温馨提示
试读
40页
提出了系统性风险的衡量标准:CoVaR,金融系统的风险价值(VaR),以机构陷入困境为条件。 认为一个机构对系统性风险的贡献是CoVaR之间的差异条件 关于受困的机构和机构中间状态的CoVaR。 根据我们对公开交易金融机构领域的CoVaR的估计,我们量化了杠杆等特征的程度, 规模和期限错配预测系统性风险贡献。 我们表明,预测的系统性风险贡献是反周期的,并且基于这些特征预测系统性风险贡献的程度,主张宏观审慎监管。
资源推荐
资源详情
资源评论
CoVaR
Tobias Adrian
y
Federal Reserve Bank of New York
z
Markus K. Brunnermeier
x
Princeton University
This Version: November 1, 2010
Abstract
We propose a measure for systemic risk: CoVaR, the value at risk (VaR) of th e
…nancial system conditional on institutions being under distress. We de…ne an insti-
tution’s contribution to systemic risk as the di¤erence between CoVaR conditional
on the institution being under distress and the CoVaR in the median state of the
institution. From our estimates of CoVaR f or the universe of publicly traded …nan-
cial institutions, we quantify the extent to which characteristics such as leverage,
size, and maturity mismatch predict systemic risk contribution. We show that pre-
dicted systemic risk contribution is countercyclical, and argue for macroprudential
regulation based on the degree to which such characteristics predict systemic risk
contribution.
Keywords: Value at Risk, Systemic Risk, Adverse Feedback Loop, E ndogen ous
Risk, Risk Spillovers, Financial Architecture, Capital Requirements
JEL classi…cation: G01, G10, G18, G20, G28, G32, G38
Special thanks go to Daniel Green and Hoai-Luu Nguyen for outstanding research assistance. The
authors also thank Paolo Angelini, Gadi Barlevy, René Carmona, Stephen Brown, Robert Engle, Mark
Flannery, Xavier Gabaix, Paul Glasserman, Beverly Hirtle, Jon Danielson, John Kambhu, Arvind Kr-
ishnamurthy, Bu rton Malkiel, Maureen O’Hara, Andrew Patton, Matt Pritsker, Matt Richardson, Jean-
Charles Rochet, José Scheinkman, Jeremy Stein, Kevin Stiroh, and Skander Van den Heuvel for feedback,
as well as seminar participants at numerous universities, c entral banks, and conferences. We are grateful
for support from the Institute f or Quantitative Investment Research Europe. Brunnermeier also acknowl-
edges …nancial support from the Alfred P. Sloan Foundation. An earlier version of this paper with the
de…nition of CoVaR was presented at the NBER Summer Institute under the title “Risk Spillovers of
Financial Institutions”in July 2008.
y
Federal Reserve Bank of New York, Capital Markets, 33 Liberty Street, New York, NY 10045,
http://nyfedeconomists.org/adrian, e-mail: tobias.adrian@ny.frb.org.
z
The views expressed in this paper are those of the authors and do not necessarily represent those of
the Federal Reserve Bank of New York or the Federal Reserve System.
x
Princeton University, Department of Economics, Bendheim Center for Finance, Princeton, NJ 08540-
5296, NBER, CEPR, CESIfo, http://www.princeton.edu/~markus, e-mail: markus@princeton.edu.
1 Introduction
During times of …nancial crises, losses tend to spread across …nancial institutions, threat-
ening the …nancial system as a whole.
1
While comovement of …nancial institutions’assets
and liabilities is primarily driven by fundamentals in normal times, comovement tends
to increase during times of crisis. Such increases of comovement give rise to systemic
risk— the risk that institutional distress spreads widely and distorts the supply of credit
and capital to the real economy. Negative spillover e¤ects can be direct, because of di-
rect contractual links and heightened counterparty credit risk, or indirect through price
e¤ects via liquidity spirals. Measures of systemic risk that capture the increase in tail
comovement during …nancial crises should become supervisory tools and form the basis
of any macroprudential regulation.
The most common measure of risk used by …nancial institutions— the value at risk
(VaR)— focuses on the risk of an individual institution in isolation. The q%-VaR is
the maximum dollar loss within the q%-con…dence interval; see the overviews by Kupiec
(2002) and Jorion (2006). However, a single institution’s risk measure does not necessarily
re‡ect systemic risk— the risk that the stability of the …nancial system as a whole is
threatened. First, according to the classi…cation in Brunnermeier, Crocket, Goodhart,
Perssaud, and Shin (2009), a systemic risk measure should identify the risk on the system
by “individually systemic”institutions, which are so interconnected and large that they
can cause negative risk spillover e¤ects on others, as well as by institutions that are
“systemic as part of a herd.” A group of 100 institutions that act like clones can be as
precarious and dangerous to the system as the large merged identity. The S&L crisis in the
1980s is a prominent example of many small institutions being systemic as part of herd.
1
Examples include the 1987 equity market crash, which was started by portfolio hedging of pension
funds and led to substantial losses of investment banks; the 1998 crisis, which was started with losses of
hedge funds and spilled over to the trading ‡oors of commercial and investment banks; and the 2007-09
crisis, which spread from SIVs to commercial banks and on to investment banks and hedge funds. See
Brady (1988), Rubin, Greenspan, Levitt, and Born (1999), Brunnermeier (2009), and Adrian and Shin
(2010a).
1
Second, risk measures should recognize that risk typically builds up in the background in
the form of imbalances and bubbles and materializes only during a crisis. Hence, high-
frequency risk measures that rely primarily on contemporaneous price movements are
misleading and procyclical. Regulation based on such contemporaneous measures tends
to be procyclical and potentially ampli…es business cycles (see Adrian and Shin (2010b)).
The objective of this paper is twofold: First, we propose a measure for systemic risk.
Second, we outline a method that allows for a countercyclical implementation of macro-
prudential policy by predicting future systemic risk using current institutional character-
istics such as size, leverage, and maturity mismatch. To emphasize the systemic nature
of our risk measure, we add to existing risk measures the pre…x “Co,” which stands for
conditional, comovement, contagion, or contributing. We focus primarily on CoVaR,
where institution i’s CoVaR relative to the system is de…ned as the VaR of the whole
…nancial sector conditional on institution i being in distress.
2
The di¤erence between
the CoVaR conditional on the distress of an institution and the CoVaR conditional on
the “normal”state of the institution, CoVaR, captures the marginal contribution of a
particular institution (in a non-causal sense) to the overall systemic risk.
There are several advantages to our CoVaR measure. First, while CoVaR focuses
on the contribution of each institution to overall system risk, current prudential regulation
focuses on the risk of individual institutions. Regulation based on the risk of institutions in
isolation can lead, in the aggregate, to excessive risk-taking along systemic risk dimensions.
To see this more explicitly, consider two institutions, A and B, which report the same VaR,
but for institution A the CoVaR= 0, while for institution B the CoVaR is large (in
absolute value). Based on their VaRs, both institutions appear equally risky. However,
the high CoVaR of institution B indicates that it contributes more to system risk. Since
2
Just as VaR sounds like variance, CoVaR sounds like covariance. This analogy is no coincidence.
In fact, under many distributional assumptions (such as the assumption that shocks are conditionally
Gaussian), the VaR of an institution is indeed proportional to the variance of the institution, and the
CoVaR of an institution is proportional to the covariance of the …nancial system and the individual
institution.
2
system risk might carry a higher risk premium, institution B might outshine institution
A in terms of generating returns, so that competitive pressure might force institution A
to follow suit. Imposing stricter regulatory requirements on institution B would break
this tendency to generate systemic risk.
One could argue that regulating institutions’VaR might be su¢ cient as long as each
institution’s CoVaR goes hand in hand with its VaR. However, this is not the case, as
(i) it is not desirable that institution A should increase its contribution to systemic risk
by following a strategy similar to institution B and (ii) empirically, there is no one-to-one
connection between an institution’s CoVaR (y-axis) and its VaR (x-axis), as Figure 1
shows. Overall, Figure 1 questions the usefulness of bank regulation to rely primarily on
VaR.
CFC
WB
BAC
JPM
C
WFC
BSC
MER
MS
LEH
GS
AIG
BRK
MET
FNM
FRE
-.8 -.6 -.4 -.2 0
∆
CoVaR
-1.6 -1.4 -1.2 -1 -.8
Institution VaR
Commercial Banks Investment Banks
Insurance Companies GSEs
∆
CoVaR vs. VaR - Returns
Figure 1: The scatter plot shows the weak link between institutions’ risk in isolation,
measured by VaR
i
(x-axis), and institutions’contribution to system risk, measured by
CoVaR
i
(y-axis). The VaR
i
and CoVaR
i
are measured in 2006Q4 and are reported
in returns. A list with the names of the institutions corresponding to the tickers in this
plot is given in Appendix C.
Another advantage of our co-risk measure is that it is general enough to study the
risk spillovers across the whole …nancial network. For example, CoVaR
jji
captures the
3
Figure 2: CoVaR network structure. The top number represents the CoVaR in billions of
US dollars of the indicated institution, conditional that the institution at the origin of the
arrow is in distress. The bottom number represents the CoVaR in the opposite direction.
increase in risk of individual institution j when institution i falls into distress. To the
extent that it is causal, it captures the risk spillover e¤ects that institution i causes on
institution j. Of course, it can be that institution i’s distress causes a large risk increase
in institution j, while institution j causes almost no risk spillovers onto institution i.
That is, there is no reason why CoVaR
jji
should equal CoVaR
ijj
. Figure 2 shows the
directional e¤ects for …ve U.S. banks with large broker-dealer subsidiaries, as of 2006Q4.
Another advantage of the CoVaR de…nition is that it is readily extendible from a
value at risk measure to other tail risk measures. Several authors have pointed out short-
comings of VaR and argued in favor of alternative risk measures. One of these measures
is the expected shortfall (ES), which captures the expected loss beyond the q% quantile.
It is straightforward to extend our approach to other risk measures, e.g. the co-expected
shortfall (Co-ES). The advantage of Co-ES relative to CoVaR is that it provides less
incentive to load on to tail risk below the percentile that de…nes the VaR or CoVaR.
While the economic arguments of this paper are readily translatable to expected shortfall,
this might not matter much in practice, as both CoVaR and Co-ES can be monitored
4
剩余39页未读,继续阅读
资源评论
weixin_44569967
- 粉丝: 2
- 资源: 1
上传资源 快速赚钱
- 我的内容管理 展开
- 我的资源 快来上传第一个资源
- 我的收益 登录查看自己的收益
- 我的积分 登录查看自己的积分
- 我的C币 登录后查看C币余额
- 我的收藏
- 我的下载
- 下载帮助
安全验证
文档复制为VIP权益,开通VIP直接复制
信息提交成功