Robustness of the Black and Scholes Formula

Consider an option on a stock whose volatility is unknown and stochastic. An agent assumes this volatility to be a specific function of time and the stock price, knowing that this assumption may result in a misspecification of the volatility. However, if the misspecified volatility dominates the true volatility, then the misspecified price of the option dominates its true price. Moreover, the option hedging strategy computed under the assumption of the misspecified volatility provides an almost sure one-sided hedge for the option under the true volatility. Analogous results hold if the true volatility dominates the misspecified volatility. These comparisons can fail, however, if the misspecified volatility is not assumed to be a function of time and the stock price. The positive results, which apply to both European and American options, are used to obtain a bound and hedge for Asian options.     

Asymptotics for small nonlinear price impact: A PDE approach to the multidimensional case

We provide an asymptotic expansion of the value function of a multidimensional utility maximization problem from consumption with small nonlinear price impact. In our model, cross‐impacts between assets are allowed. In the limit for small price impact, we determine the asymptotic expansion of the value function around its frictionless version. The leading order correction is characterized by a nonlinear second‐order PDE related to an ergodic control problem and a linear parabolic PDE. We illustrate our result on a multivariate geometric Brownian motion price model.     

Budget impact analysis for dapagliflozin in type 2 diabetes in Egypt

Abstract

Introduction: Type 2 diabetes mellitus (T2DM) is a major health problem in Egypt with a high impact on morbidity, mortality, and healthcare resources. This study evaluated the budget impact and the long-term consequences of dapagliflozin versus other conventional medications, as monotherapy, from both the societal and health insurance perspectives in Egypt.

Methods: A static budget impact model was developed to estimate the financial consequences of adopting dapagliflozin on the healthcare payer budget. We measured the direct medical costs of dapagliflozin (new scenario) as monotherapy, compared to metformin, insulin, sulphonylurea, dipeptidyl peptidase-4 (DPP-4) inhibitors, thiazolidinedione, and repaglinide (old scenarios) over a time horizon of 3 years. Myocardial infarction (MI), ischemic stroke, hospitalization for heart failure (HHF), and initiation of renal replacement therapy (RRT) rates were captured from DECLARE TIMI 58 trial. One-way sensitivity analyses were conducted.

Results: The budget impact model estimated 2,053,908 patients eligible for treatment with dapagliflozin from a societal perspective and 1,207,698 patients from the health insurance (HI) perspective. The new scenario allows for an initial savings of EGP121 million in the first year, which increased to EGP243 and EGP365 million in the second and third years, respectively. The total cumulative savings from a societal perspective were estimated at EGP731 million. Dapagliflozin allows for savings of EGP71, EGP143, and EGP215 million in the first, second and third years respectively, from the HI perspective, with total cumulative savings of EGP430 million over the 3 years.

Conclusion: Treating T2DM patients using dapagliflozin instead of conventional medications, maximizes patients’ benefits and decreases total costs due to drug cost offsets from fewer cardiovascular and renal events. The adoption of dapagliflozin is a budget-saving treatment option, resulting in substantial population-level health gains due to reduced event rate and cost savings from the perspective of the national healthcare system.     

Defying Distance? Cross‐Border Acquisitions by Emerging‐Economy Firms

We argue that emerging‐economy firms’ international location choices are driven by the pursuit of dynamic efficiency rather than the immediate minimization of transaction and learning costs, and hence the relationship between country distance and the number of cross‐border acquisitions will be less negative for these firms relative to advanced‐economy firms. We then test the hypothesis with respect to four measures of country distance—geographic, economic, cultural, and institutional—and find support for the hypothesis. Our study provides empirical support for claims in the literature about differences in the international expansion behavior of emerging‐economy firms with respect to location. In addition, our study makes a theoretical contribution by showing that the theoretical perspective of dynamic efficiency can explain the difference in the location choices for cross‐border acquisitions by emerging‐economy firms relative to those by advanced‐economy firms. © 2016 Wiley Periodicals, Inc..     

Do single‐stock circuit breakers provide a safety net for Canadian investors?

This study looks at the market impact of recent regulatory changes in Canada that provide for trading halts on individual stocks that experience large upside or downside movements. The focus is on all stocks traded on the Toronto Stock Exchange since the inception of the single‐stock circuit breaker rule (SSCB) in February 2012, to replace the short‐sale uptick rule. The results support pricing efficiency: material information that caused the circuit breaker is incorporated in stock prices on the day of the halt (neither overreaction nor underreaction), with no decline in market liquidity. Using trade‐by‐trade data constructed on five‐minute trading intervals, we refine the daily results, and show that shocks in realized volatility are focused in the 10‐minute trading interval surrounding the halts. While circuit breakers provide a limited safety net for investors when their stocks are subject to severe volatility, they do not allow for a quick turnaround for stocks experiencing severe price decline events.     

Individual and contextual predictors of team member proactivity: what do we know and where do we go from here?

Contemporary organizations are placing greater emphasis on team work in order to meet the challenges of an increasingly turbulent business environment. In this context, the relationship between team member proactivity and overall team performance has been the focus of growing interest among management scholars and practitioners alike. Whereas extant scholarship acknowledges that team member proactivity is different from other forms of proactivity (i.e., individual and organization member proactivity), there is still only limited understanding of the factors that predict team member proactivity. Therefore, this paper extends current scholarship by identifying the individual and contextual predictors of team member proactivity and explaining how, taken together, they jointly influence team member proactivity. Building on these findings, the paper also identifies gaps in the current literature and proposes a model of team member proactivity to be tested in future research.     

Entrepreneurship and income inequality: a spatial panel data analysis

The main objective of this paper is to empirically analyze the relationship between entrepreneurship and income inequality. We use a spatial panel data analysis for both 33 high-income countries and 39 middle- and low-income countries over a period of 11 years. Estimation results and rigorous diagnostic analysis suggest that: (i) there is a strong support for the existence of an inverted U-shaped relationship between entrepreneurship and income inequality espoused by the Kuznets Curve hypothesis; (ii) the relationship between entrepreneurship and income inequality is negatively moderated by country’s level of economic development; (iii) regardless of income inequality levels, entrepreneurship has a non-linear relationship with income per capita; (iv) gross domestic expenditure on research and development exhibits significant negative impacts on entrepreneurship; (v) significant mixed effects on the likelihood of entrepreneurial activity are observed with governance, globalization, population growth rate, and competitiveness variables; (vi) there are significant mixed feedback effects on entrepreneurship; and (vii) there are statistically significant, positive as well as negative spatial spillovers to country-level entrepreneurial activity.     

Out of the Closet: When Moral Identity and Protestant Work Ethic Improve Attitudes toward Advertising Featuring Same-Sex Couples

This research examines how heterosexual consumers react to advertising featuring same-sex couples. Across three studies, we find that heterosexual consumers report higher levels of disgust in response to advertising featuring same-sex couples in comparison to mixed-sex couples, which results in more negative attitudes toward the advertisement and the advertised brand. We also find that moral-identity priming reduces disgust elicited by advertising featuring same-sex couples and improves attitudes toward the advertisement and the brand. However, we find that moral-identity priming is ineffective for consumers with high social dominance orientation. For these consumers, portraying same-sex couples as possessing Protestant work ethic traits decreases disgust and improves attitudes toward the advertisement and the brand.     

Giving at the close: Experimental evidence on cooperation in contributing to a public good

We present a simple dynamic model of contributions to a public good. We test the model by conducting a public good game experiment and fundraising experiment among religious Jewish students for the procurement of sustainable supplies for their campus synagogue. The results of the experiments show a high level of cooperation; particularly, the results of the public good experiment show that contributions are above the predicted optimum. Nevertheless, in accordance with the economic theory, we find that the contribution path is upward sloping and contributions increase with the benefit of the public good. Our findings also suggest that the level of contributions and their path are affected by peer and gender effects.     

Rethinking guanxi and performance: Understanding the dark side of Sino–U.S. business relationships

Previous studies on guanxi (關係) have focused on how guanxi contributes positively to business relationships, without addressing the pivotal role that guanxi plays in managing the dark-side of business relationships. To address this knowledge gap, this study specifically investigates guanxi’s influence on conflict, opportunism, and switching intention in Sino–U.S. business relationships and examines how guanxi mediate the positive effect of performance as well as the negative effect of uncertainty on such dark-side constructs. Drawing on data from over 270 Chinese firms, the findings reveal that guanxi is undermined by relationship uncertainty but enhanced by performance, guanxi also reduces the dark-side of Sino-US business relationships. Chinese buyers’ guanxi with U.S. suppliers significantly lessens their switching intention, opportunistic behavior, and the perceived levels of conflict in Sino-US relationships. The findings explain how guanxi is employed as a tool to reduce the burden associated with the dark-side of business relationships and give relevant implications.