Markus K. Brunnermeier

This paper documents that banks with higher non-interest income (noncore activities like investment banking, venture capital and trading activities) have a higher contribution to systemic risk than traditional banking (deposit taking and lending). After decomposing total non-interest income into two components, trading income and investment banking and venture capital income, we find that both components are roughly equally related to systemic risk. These results are robust to endogeneity concerns when we use a difference-in-difference approach with the Lehman bankruptcy proxying for an exogenous shock. We also find that banks with higher trading income one-year prior to the recession earned lower returns during the recession period. No such significant effect was found for investment banking and venture capital income.

Traditional economics argues that financial derivatives, like CDOs and CDSs, ameliorate the negative costs imposed by asymmetric information. This is because securitization via derivatives allows the informed party to find buyers for less information-sensitive part of the cash flow stream of an asset (e.g., a mortgage) and retain the remainder. In this paper we show that this viewpoint may need to be revised once computational complexity is brought into the picture. Using methods from theoretical computer science this paper shows that derivatives can actually amplify the costs of asymmetric information instead of reducing them. Note that computational complexity is only a small departure from full rationality since even highly sophisticated investors are boundedly rational due to a lack of requisite computational resources.

This paper provides a theory of money, whose value depends on the functioning of the intermediary sector, and a unified framework for analyzing the interaction between price and financial stability. Households that happen to be productive in this period finance their capital purchases with credit from intermediaries and from their own savings. Less productive household save by holding deposits with intermediaries (inside money) or outside money. Intermediation involves risk-taking, and intermediaries' ability to lend is compromised when they suer losses. After an adverse productivity shock, credit and inside money shrink, and the value of (outside) money increases, causing de
ation that hurts borrowers even further. An accommodating monetary policy in downturns can mitigate these destabilizing adverse feedback effects. Lowering short-term interest rates increases the value of long-term bonds, recapitalizes the intermediaries by redistributes wealth. While this policy helps the economy ex-post, ex-ante it can lead to excessive risk-taking by the intermediary sector.

This paper studies the full equilibrium dynamics of an economy with financial frictions. Due to highly non-linear amplication eects, the economy is prone to instability and occasionally enters volatile episodes. Risk is endogenous and asset price correlations are high in down turns. In an environment of low exogenous risk experts assume higher leverage making the system more prone to systemic volatility spikes - a volatility paradox. Securitization and derivatives contracts leads to better sharing of exogenous risk but to higher endogenous systemic risk. Financial experts may impose a negative externality on each other by not maintaining adequate capital cushion.

This article surveys the macroeconomic implications of financial frictions. Financial frictions lead to persistence and when combined with illiquidity to non-linear amplification eects. Risk is endogenous and liquidity spirals cause financial instability. Increasing margins further restrict leverage and exacerbate the downturn. A demand for liquid assets and a role for money emerges. The market outcome is generically not even constrained ecient and the issuance of government debt can lead to a Pareto improvement. While financial institutions can mitigate frictions, they introduce additional fragility and through their erratic money creation harm price stability.

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We develop a model of endogenous maturity structure for financial institutions that borrow from multiple creditors. We show that a maturity rat race can occur: an individual creditor can have an incentive to shorten the maturity of his own loan to the institution, allowing him to adjust his financing terms or pull out before other creditors can. This, in turn, causes all other lenders to shorten their maturity as well, leading to excessively short-term financing. This rat race occurs when interim information is mostly about the probability of default rather than the recovery in default, and is most pronounced during volatile periods and crises. Overall, firms are exposed to unnecessary rollover risk.

In many situations, timing is crucial—individuals face a trade-off between gains from waiting versus the risk of being preempted. To examine this, we offer a model of clock games, which we then test experimentally. Each player's clock starts upon receiving a signal about a payoff-relevant state variable. Since the timing of the signals is random, clocks are de-synchronized. A player must decide how long, if at all, to delay his move after receiving the signal. We show that (i) delay decreases as clocks become more synchronized, and (ii) when moves are observable, players “herd” immediately after any player makes a move. Our experimental results are broadly consistent with these two key predictions of the theory.

Should we regulate complex securities, subject them to an FDA-style approval process, or limit who can invest in them? To answer these questions, one first needs to establish why complexity matters, and what defines a complex security. Complexity is an important concept in financial markets with boundedly rational agents, but that finding a workable definition of complexity is difficult. For example, while CDOs are viewed by most as highly complex, equity shares of financial institutions, whose payoff structures are even more complicated, are often seen as less complex. We point out three different ways in which boundedly rational investors can deal with complexity: (i) by dividing up difficult problems into smaller sub-problems or by using separation results, (ii) by using models – simplified pictures of reality, (iii) through standardization and commoditization of securities. Importantly, simply increasing the quantity of information disclosed to investors does not resolve complexity, since in the presence of bounded rationality it leads to information overload..

This paper summarizes and explains the main events of the liquidity and credit crunch in 2007-08. Starting with the trends leading up to the crisis, I explain how these events unfolded and how four different amplification mechanisms magnified losses in the mortgage market into large dislocations and turmoil in financial markets.

We provide a model that links an asset's market liquidity (i.e., the ease with which it is traded) and traders' funding liquidity (i.e., the ease with which they can obtain funding). Traders provide market liquidity, and their ability to do so depends on their availability of funding. Conversely, traders' funding, i.e., their capital and margin requirements, depends on the assets' market liquidity. We show that, under certain conditions, margins are destabilizing and market liquidity and funding liquidity are mutually reinforcing, leading to liquidity spirals. The model explains the empirically documented features that market liquidity (i) can suddenly dry up, (ii) has commonality across securities, (iii) is related to volatility, (iv) is subject to “flight to quality,” and (v) co-moves with the market. The model provides new testable predictions, including that speculators' capital is a driver of market liquidity and risk premiums.

When a firm is unable to roll over its debt, it may have to seek more expensive sources of financing or even liquidate its assets. This paper provides a normative analysis of minimizing such rollover risk, through the optimal dynamic choice of the maturity structure of debt. The objective of a firm with long-term assets is to maximize the effective maturity of its liabilities across several refinancing cycles, rather than to maximize the maturity of the current bonds outstanding. An advantage of short-term financing is that a firm, while in good financial health, can readjust its maturity structure more quickly in response to changes in its asset value.

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We use data from the Panel Study of Income Dynamics to investigate how households' portfolio allocations change in response to wealth fluctuations. Persistent habits, consumption commitments, and subsistence levels can generate time-varying risk aversion with the consequence that when the level of liquid wealth changes, the proportion a household invests in risky assets should also change in the same direction. In contrast, our analysis shows that the share of liquid assets that households invest in risky assets is not affected by wealth changes. Instead, one of the major drivers of household portfolio allocation seems to be inertia: households rebalance only very slowly following inflows and outflows or capital gains and losses.

People tend to underestimate the work involved in completing tasks and consequently finish tasks later than expected or do an inordinate amount of work right before projects are due. We present a theory in which people underpredict and procrastinate because the ex-ante utility benefits of anticipating that a task will be easy to complete outweigh the average ex-post costs of poor planning. We show that, given a commitment device, people self-impose deadlines that are binding but require less smoothing of work than those chosen by a person with objective beliefs. We test our theory using extant experimental evidence on differences in expectations and behavior. We find that reported beliefs and behavior generally respond as our theory predicts. For example, monetary incentives for accurate prediction ameliorate the planning fallacy while incentives for rapid completion aggravate it.

What makes a good leader? A good leader is able to coordinate his followers around a credible mission statement, which communicates the future course of action of the organization. In practice, leaders learn about the best course of action for the organization over time. While learning helps improve the organization's goals it also creates a time-consistency problem. Leader resoluteness is a valuable attribute in such a setting, since it slows down the leader's learning and thus improves the credibility of the mission statement. But resolute leaders also inhibit communication with followers and leader resoluteness is costly when followers have sufficiently valuable signals.