A model of optimal portfolio selection under liquidity risk and price impact

We study a financial model with one risk-free and one risky asset subject to liquidity risk and price impact. In this market, an investor may transfer funds between the two assets at any discrete time. Each purchase or sale policy decision affects the rice of the risky asset and incurs some fixed transaction cost. The objective is to maximize the expected utility from terminal liquidation value over a finite horizon and subject to a solvency constraint. This is formulated as an impulse control problem under state constraints and we characterize the value function as the unique constrained viscosity solution to the associated quasi-variational Hamilton–Jacobi–Bellman inequality. We would like to thank Mihail Zervos for useful discussions.     

Annuitization and aggregate mortality risk

It is well established that annuities can fully diversify idiosyncratic mortality risks. However, survival rates at the cohort level are changing, raising the question what is the scope of annuities in the presence of aggregate mortality risk? In an overlapping generations setting, we show that risk free annuities exist, but offer a return below the (fair) certainty equivalent return, and agents do not fully annuitize their savings. Higher aggregate mortality risk increases savings and thus the mean level of the capital stock. This lowers the mean rate of return on capital, the survival premium on annuities and the share of individual savings in annuities.     

Parameter risk in time-series mortality forecasts

The projection of mortality rates is an essential part of valuing liabilities in life insurance portfolios and pension schemes. An important tool for risk management and solvency purposes is a stochastic projection model. We show that ARIMA models can be better representations of mortality time-series than simple random-walk models. We also consider the issue of parameter risk in time-series models from the point of view of an insurer using them for regulatory risk reporting – formulae are given for decomposing overall risk into undiversifiable trend risk (parameter uncertainty) and diversifiable volatility. Particular attention is given to the contrasts in how academic researchers might view these models and how insurance regulators and practitioners in life offices might use them. Using a bootstrap method we find that, while certain kinds of parameter risk are negligible, others are too material to ignore. We also find that an objective model selection criterion, such as goodness of fit to past data, can result in the selection of a model with unstable parameter values. While this aspect of the model is superficially undesirable, it also leads to slightly higher capital requirements and thus makes the model of keen interest to regulators. Our conclusions have relevance to insurers using value-at-risk capital assessments in the European Union under Solvency II, but also territories using conditional tail expectations such as Australia, Canada and Switzerland.     

Spectral risk measures and portfolio selection

This paper deals with risk measurement and portfolio optimization under risk constraints. Firstly we give an overview of risk assessment from the viewpoint of risk theory, focusing on moment-based, distortion and spectral risk measures. We subsequently apply these ideas to an asset management framework using a database of hedge funds returns chosen for their non-Gaussian features. We deal with the problem of portfolio optimization under risk constraints and lead a comparative analysis of efficient portfolios. We show some robustness of optimal portfolios with respect to the choice of risk measure. Unsurprisingly, risk measures that emphasize large losses lead to slightly more diversified portfolios. However, risk measures that account primarily for worst case scenarios overweight funds with smaller tails which mitigates the relevance of diversification.     

The impact of multiple structural changes on mortality predictions

Most mortality models proposed in recent literature rely on the standard ARIMA framework (in particular: a random walk with drift) to project mortality rates. As a result the projections are highly sensitive to the calibration period. We therefore analyse the impact of allowing for multiple structural changes on a large collection of mortality models. We find that this may lead to more robust projections for the period effect but that there is only a limited effect on the ranking of the models based on backtesting criteria, since there is often not yet sufficient statistical evidence for structural changes. However, there are cases for which we do find improvements in estimates and we therefore conclude that one should not exclude on beforehand that structural changes may have occurred.     

Trading frenzies and their impact on real investment

We study a model in which a capital provider learns from the price of a firm's security in deciding how much capital to provide for new investment. This feedback effect from the financial market to the investment decision gives rise to trading frenzies, in which speculators all wish to trade like others, generating large pressure on prices. Coordination among speculators is sometimes desirable for price informativeness and investment efficiency, but speculators' incentives push in the opposite direction, so that they coordinate exactly when it is undesirable. We analyze the effect of various market parameters on the likelihood of trading frenzies to arise.     

Women in the boardroom and their impact on governance and performance

We show that female directors have a significant impact on board inputs and firm outcomes. In a sample of US firms, we find that female directors have better attendance records than male directors, male directors have fewer attendance problems the more gender-diverse the board is, and women are more likely to join monitoring committees. These results suggest that gender-diverse boards allocate more effort to monitoring. Accordingly, we find that chief executive officer turnover is more sensitive to stock performance and directors receive more equity-based compensation in firms with more gender-diverse boards. However, the average effect of gender diversity on firm performance is negative. This negative effect is driven by companies with fewer takeover defenses. Our results suggest that mandating gender quotas for directors can reduce firm value for well-governed firms.     

Stroke--incidence, mortality, morbidity and risk

In the United States, 700,000 strokes, responsible for 165,000 deaths, occur each year. Worldwide, stroke is the 2nd leading cause of death. Stroke is a major health problem; and as the population ages, its significance will grow. This paper reviews the epidemiology of stroke, the identification of modifiable risk factors, and some of the options for intervention that can reduce stroke-related mortality and morbidity. Though the diagnosis and care of stroke patients has improved, mortality resultant from stroke remains significant, with only 50% 5-year survival in some clinical studies. The risk of stroke following a transient ischemic attack (TIA) or initial stroke is also significant-approximately 30% following either event. Stroke severity at onset and patient age are the most important factors for predicting prognosis. Stroke prevention focuses on management of the traditional cardiovascular risk factors especially control of blood pressure and smoking cessation. The role of diabetes and lipid control in stroke prevention continues to be studied. The optimum use of anticoagulation to reduce stroke risk has been explored by the Stroke in Patients with Atrial Fibrillation (SPAF) studies. Carotid endarterectomy is effective in stroke prevention for those with symptomatic carotid obstruction of 70%, but its role in other scenarios is less certain. Antiplatelet drugs continue to be an important therapy for the prevention of recurrent stroke. Centralized stroke centers that specialize in stroke diagnosis and care along with rapidly rendering appropriate treatment can improve mortality and morbidity of stroke by 20%.     

The impact of regulation on market risk

While it is crucial to understand the impact of regulatory changes on market risk, the literature does not show how risk responds to expected regulatory changes that are specifically designed to change risk. Our paper fills this gap by providing a detailed study of one such case. Using both a sample of privatized U.K. companies, and U.K. and U.S. control portfolios, between 1993 and 2000, we show (both for the single-factor market model and the three-factor Fama-French model) that the observed changes in market risk are significant and consistent with theory.     

The impact of risk and uncertainty on expected returns

We study asset pricing in economies featuring both risk and uncertainty. In our empirical analysis, we measure risk via return volatility and uncertainty via the degree of disagreement of professional forecasters, attributing different weights to each forecaster. We empirically model the typical risk-return trade-off and augment these models with our measure of uncertainty. We find stronger empirical evidence for an uncertainty-return trade-off than for the traditional risk-return trade-off. Finally, we investigate the performance of a two-factor model with risk and uncertainty in the cross section.     

Banks recapitalization policies in Japan and their impact on the market

The following measures to boost banks’ capital were implemented from December 1997 through March 1998 in Japan: (1) Banks were given the option to choose the cost method in the valuation of their equity portfolios. (2) Reevaluation of bank property assets at current market values was introduced. (3) Public funds were injected into the banking system. This article examines whether or not the announcements of these measures have had any impact on stock prices. We find: (1) The announcement of the introduction of the cost method in the valuation of equity portfolios had a limited effect on stock prices. (2) The announcement of reevaluation of property assets had a relatively strong impact on stock prices. (3) The aim of capital injection by the government might be interpreted by investors in general as an attempt to favor weak banks rather than to bolster the capital base of strong banks.     

Prudential policies and their impact on credit in the United States

We analyze how two types of recently used prudential policies affected the supply of credit in the United States. First, we test whether the U.S. bank stress tests had any impact on the supply of mortgage credit. We find that initiation of the Comprehensive Capital Analysis and Review (CCAR) stress tests in 2011 had a negative effect on the share of jumbo mortgage originations and approval rates at stress-tested banks, whereby banks with worse capital positions were impacted more negatively. Second, we analyze the impact of the 2013 Supervisory Guidance on Leveraged Lending and subsequent 2014 FAQ notice, which clarified expectations on the Guidance. We find that the institution-specific share of speculative-grade term-loan originations decreased notably at regulated banks after the FAQ notice, especially at banks with greater market share for such loans.     

Detecting and modelling the jump risk of CO2 emission allowances and their impact on the valuation of option on futures contracts

Modelling CO₂ emission allowance prices is important for pricing CO₂ emission allowance linked assets in the emissions trading scheme (ETS). Some statistical properties of CO₂ emission allowance prices have been discovered in the literature ignoring price jumps. By employing real data from the ETS, this research first detects the jump risk using a jump test and then verifies jump effects in modelling CO₂ emission allowance prices by comparing the in-sample and out-of-sample model performance. We suggest a model which can capture the statistical properties of autocorrelation, volatility clustering and jump effects is more appropriate for modelling CO₂ emission allowance prices. We establish a general framework for pricing CO₂ emission allowance options on futures contracts with these properties and find that the jump risk significantly affects the value of the CO₂ emission allowance option on futures contracts. More importantly, we demonstrate that the dynamic jump ARMA–GARCH model can provide more accurate valuations of the CO₂ emission allowance options on futures than other models in terms of pricing error.     

Credit risk management at retail in Mexico: An econometric improvement in the selection of variables and changes in their characteristics

The early prediction of bad debtors for revolving credits in Mexico is a relevant issue today. The credit behavior econometric model proposed considers the changes in the characteristics of the consolidated accredited and provides better results than those obtained with the methodology utilized by the CNBV on provision matters. The results obtained show that the possibility of replacing the current model, minimizing the expected loss and increasing the ROA per financial institution at a national level by 2.20%, complies with the methodological criteria and the statistical tests in accordance with the Compiled Banking Regulation and Basel II guidelines on credit risk issues.     

Size and diversity in VC syndicates and their impact on IPO performance

This paper investigates the impact of venture capital (VC) syndicate size and composition on the IPO and post-IPO performances of investee companies in an attempt to shed some light on the extent to which larger and more diverse syndicates are more likely to suffer from internal agency problems which might hinder the decision-making process and lead to less value added for their portfolio companies. The question is of great relevance because, while the vast majority of the empirical literature compares VC backed IPOs with non-VC backed ones, most VC funding is provided by syndicates of two or more financiers. We construct alternative measures of size as well as diversity based on several VC characteristics such as age, geographic location, type and affiliation of VC firms and find that larger and more diverse syndicates are associated with higher underpricing and lower valuation at the IPO date. Furthermore, we provide evidence that that diversity and size are negatively correlated to the long-term performance of the IPO firms and this finding is robust to several alternative measures of long-term performance.