Artificial Intelligence,Education, and Entrepreneurship

We document an unprecedented brain drain of Artificial Intelligence (AI) professors from universities from 2004 to 2018. We find that students from the affected universities establish fewer AI startups and raise less funding. The brain-drain effect is significant for tenured professors, professors from top universities, and deep-learning professors. Additional evidence suggests that unobserved city- and university-level shocks are unlikely to drive our results. We consider several economic channels for the findings. The most consistent explanation is that professors' departures reduce startup founders' AI knowledge, which we find is an important factor for successful startup formation and fundraising.     

Developers, Herding, and Overbuilding

Recent years have seen the most pronounced turbulence that real estate markets have ever experienced. There have been wild swings in prices, a wave of foreclosures, countless failed investments, and massive overbuilding. This paper will be primarily concerned with overbuilding. Of the many forces that may have combined to produce this situation, the paper will focus on rational overbuilding carried out by developers whose decisions are made under uncertainty. We will establish the possibility of both statistical and reputation-based herding. The former refers to developers learning from each other, and so tending to copy. The latter refers to developers copying each other in order to reduce the probability of a loss of reputation that can result from making an unconventional choice.     

Signaling,network externalities,and subsidies

A signal may be more effective the greater the number of people who use the same signal, thereby creating a network externality and potentially generating multiple equilibria. A subsidy to the signal can increase efficiency, and the signalers may benefit from the subsidy even if they pay taxes to finance it. But people who benefit from the signal may oppose too large a subsidy, because a large subsidy could destroy the signaling value.     

Money, intermediation, and banking

The business of money creation is conceptually distinct from that of intermediation. Yet, these two activities are frequently—but not always—combined together in the form of a banking system. We develop a simple model to examine the question: When is banking essential? There is a role for money due to a lack of record-keeping and a role for intermediation due to the existence of private information: both money and intermediation are essential. When monitoring costs associated with intermediation are sufficiently low, the two activities can be separated from one another. However, when monitoring costs are sufficiently high, a banking system that combines these two activities is essential.     

Uncertainty,Incentives, and Misallocation

This paper identifies a new propagation mechanism by which the effects of business cycle shocks amplify in the context of the dynamic stochastic general equilibrium framework. Business cycle shocks, such as heightened uncertainty, and positive monetary shocks endogenously magnify the cross-sectional dispersion in idiosyncratic productivity. This induces entrepreneurs, who have asset substitution incentive, to distort the quality of an investment project, which amplifies the response of investment and output. Moreover, lenders reallocate credit from firms with a high marginal product of capital, in which the asset substitution problem is more prevalent, to firms with a low marginal product of capital, which in turn further depresses aggregate economic activities. A policy that subsidizes lenders to firms with a high marginal product during a recession improves the allocation of loans. Empirical evidence from the NBER-CES Manufacturing Industry Database provides support for the model's predictions.     

Institutional trading, information production, and the choice between spin-offs, carve-outs, and tracking stock issues

We analyze a firm's choice between spin-offs, equity carve-outs, and tracking stock issues and the role of institutional investors in corporate restructuring. We model a firm with two divisions. Insiders have private information about firm value and face an equity market with retail and institutional investors. We show that restructuring increases information production by institutional investors (relative to that about the consolidated firm): the highest increase in information production arises from spin-offs, the next highest from carve-outs, and the lowest from tracking stock issues. Insiders with the most favorable private information implement spin-offs; those with less favorable private information implement carve-outs; those with even less favorable private information implement tracking stock issues; and those with unfavorable private information remain consolidated. We explain the positive announcement effect and increase in analyst coverage associated with all three forms of restructuring. Our model also generates a number of novel testable predictions for firms' choice between spin-offs, carve-outs, and tracking stock issues, and for institutional trading around these three forms of restructuring.     

Cross-ownership,returns, and voting in mergers

We show that institutional shareholders of acquiring companies on average do not lose money around public merger announcements, because they hold substantial stakes in the targets and make up for the losses from the acquirers with the gains from the targets. Depending on their holdings in the target, acquirer shareholders generally realize different returns from the same merger, some losing money and others gaining. This conflict of interest is reflected in the mutual fund voting behavior: In mergers with negative acquirer announcement returns, cross-owners are significantly more likely to vote for the merger.     

Sensation Seeking, Overconfidence, and Trading Activity

This study analyzes the role that two psychological attributes—sensation seeking and overconfidence—play in the tendency of investors to trade stocks. Equity trading data from Finland are combined with data from investor tax filings, driving records, and mandatory psychological profiles. We use these data, obtained from a large population, to construct measures of overconfidence and sensation seeking tendencies. Controlling for a host of variables, including wealth, income, age, number of stocks owned, marital status, and occupation, we find that overconfident investors and those investors most prone to sensation seeking trade more frequently.     

Hedging,speculation, and shareholder value

We document that gold mining firms have consistently realized economically significant cash flow gains from their derivatives transactions. We conclude that these cash flows have increased shareholder value since there is no evidence of an offsetting adjustment in firms’ systematic risk. This finding contradicts a central assumption in the risk management literature that derivatives transactions have zero net present value, and highlights an important motive for firms to use derivatives that the literature has hitherto ignored. Although we find considerable evidence of selective hedging in our sample, the cash flow gains from selective hedging appear to be small at best.     

Financial Market Fragmentation and Reforms in Ghana, Malawi, Nigeria, and Tanzania

This article reports the findings from surveys of formal andinformal institutions and their clients in Ghana, Malawi, Nigeria,and Tanzania. It investigates the hypothesis that reformingfinancially repressive policies would not be sufficient to overcomefragmentation of financial markets because of structural andinstitutional barriers to interactions across different marketsegments. The four countries have substantially fragmented financialmarkets, with weak linkages between formal and informal segmentsand interest rate differentials that cannot be adequately explainedby differences in costs and risks. Nevertheless, the relativelylow transaction costs and loan losses of informal institutionsindicate that they provide a reasonably efficient solution toinformation, transaction cost, and enforcement problems thatexclude their clients from access to formal banking services.The findings imply that financial liberalization and bank restructuringin the African context should be accompanied by complementarymeasures to address institutional and structural problems, suchas contract enforcement and information availability, and toimprove the integration of informal and formal financial markets.     

Infrequent Rebalancing,Return Autocorrelation,and Seasonality

A model of infrequent rebalancing can explain specific predictability patterns in the time series and cross‐section of stock returns. First, infrequent rebalancing produces return autocorrelations that are consistent with empirical evidence from intraday returns and new evidence from daily returns. Autocorrelations can switch sign and become positive at the rebalancing horizon. Second, the cross‐sectional variance in expected returns is larger when more traders rebalance. This effect generates seasonality in the cross‐section of stock returns, which can help explain available empirical evidence.     

Options,Taxes, and Ex-Dividend Day Behavior

A novel way of estimating the expected as opposed to the actual share price fall-off is developed using option prices. This method is applied to the UK Traded Options Market using data from 1979 to 1984. The results show that: (a) the average expected fall-off implicit in option prices is around 55 to 60% of the dividend and significantly different from it. The fall-off also varied inversely with the dividend yield, which is consistent with the prediction of the “tax clientele hypothesis.” (b) The estimates of the expected fall-off were not significantly different from the actual fall-off. (c) Finally, the results imply that the usual assumption made in valuing options on dividend-paying stocks, that the fall-off is equal to the dividend, would lead to downward-biased estimates of the option value.     

Learning, Asset-Pricing Tests, and Market Efficiency

This paper studies the asset-pricing implications of parameter uncertainty. We show that, when investors must learn about expected cash flows, empirical tests can find patterns in the data that differ from those perceived by rational investors. Returns might appear predictable to an econometrician, or appear to deviate from the Capital Asset Pricing Model, but investors can neither perceive nor exploit this predictability. Returns may also appear excessively volatile even though prices react efficiently to cash-flow news. We conclude that parameter uncertainty can be important for characterizing and testing market efficiency.     

The Growing Relationship Between China and Sub-Saharan Africa: Macroeconomic, Trade, Investment, and Aid Links

China's economic ascendance over the past two decades has generatedripple effects in the world economy. Its search for naturalresources to satisfy the demands of industrialization has ledit to Sub-Saharan Africa. Trade between China and Africa in2006 totaled more than $50 billion, with Chinese companies importingoil from Angola and Sudan, timber from Central Africa, and copperfrom Zambia. Demand from China has contributed to an upwardswing in prices, particularly for oil and metals from Africa,and has given a boost to real GDP in Sub-Saharan Africa. Chineseaid and investment in infrastructure are bringing desperatelyneeded capital to the continent. At the same time, however,strong Chinese demand for oil is contributing to an increasein the import bill for many oil-importing Sub-Saharan Africancountries, and its exports of low-cost textiles, while benefitingAfrican consumers, is threatening to displace local production.China poses a challenge to good governance and macroeconomicmanagement in Africa because of the potential Dutch diseaseimplications of commodity booms. China presents both an opportunityfor Africa to reduce its marginalization from the global economyand a challenge for it to effectively harness the influx ofresources to promote poverty-reducing economic development athome. JEL codes: F01, F35, F41, N55, N57, Q33, Q43     

Returns,Volatilities, and Correlations Across Mature,Regional, and Frontier Markets: Evidence from South Asia

We investigate returns, volatilities, and correlations across mature, dominant regional, and frontier equity markets. Standard & Poor's 500 is chosen as a mature equity market; India is chosen as a dominant regional market; and Bangladesh, Pakistan, and Sri Lanka are chosen as frontier markets. Our empirical tests show that the frontier markets remain fundamentally decoupled from the mature markets during normal market periods. During turbulent times, the contagion effects from the mature to the frontier markets become more pronounced. The results suggest that the dominant regional market plays a key role in disseminating shocks across the frontier markets during normal periods; during the turbulent recent financial crisis period, a similar contagion is not observed.     

Patent rights,innovation, and firm exit

We study the causal impact of patent invalidation on subsequent innovation and exit by patent holders. The analysis uses patent litigation data from the US Federal Circuit Court and exploits random allocation of judges to control for endogeneity of the decision. Invalidation causes patent holders to reduce patenting over a five‐year window by 50% on average, but the effect is heterogeneous. The impact is large for small‐ and medium‐sized firms, particularly where they face many large competitors, and for patents central to their research portfolio. We find no significant effect for large firms. Invalidation also increases exit from patenting by small firms.     

Work Ethic, Employment Contracts, and Firm Value

We analyze how the work ethic of managers impacts a firm's employment contracts, riskiness, growth potential, and organizational structure. Flat contracts are optimal for diligent managers because they reduce risk-sharing costs, but they attract egoistic agents who shirk and unskilled agents who add no value. Stable, bureaucratic firms with low growth potential are more likely to gain value from managerial diligence. Firms that hire from a virtuous pool of agents are more conservative in their investments and have a horizontal corporate structure. Our theory also yields several testable implications that distinguish it from standard agency models.     

Household portfolio allocation,uncertainty, and risk

Analysing the Panel Study of Income Dynamics and the Health and Retirement Study, we investigate the extent to which US households reduce their financial risk exposure when confronted with background risk. Our novel modelling approach – termed a deflated ordered fractional model – quantifies how the overall composition of a household portfolio with three asset classes adjusts with background risk, and is unique in recovering for any given risky asset class the shares that are reallocated to each safer asset category. Background risk exerts a significant impact on household portfolios, inducing a ‘flight from risk’ from riskier to safer assets.