This paper surveys the growing literature on payments. We begin by presenting a simple model that illustrates the essential function of payments and how this may be implemented through various arrangements. We show how the basic models of payments have been used to address a variety of microeconomic and macroeconomic policy issues. We then discuss the links between payments economics and other fields, including monetary theory, corporate finance, and industrial organization. We conclude with an overview of the empirical literature and directions for future research.

This paper investigates whether functional diversification is value-enhancing or value-destroying in the financial services sector, broadly defined. Based on a U.S. dataset comprising approximately 4060 observations covering the period 1985–2004, we report a substantial and persistent conglomerate discount among financial intermediaries. Our results suggest that it is diversification that causes the discount, and not that troubled firms diversify into other more promising areas. In addition, the discount applies to all financial services activity-areas with the exception of investment banking and is stable over different combinations of financial activity-areas with the exception of commercial banking units combined with insurance companies and/or investment banking activities.

Size matters in banking. In this paper, we explore whether shocks originating at large banks affect the probability of distress of smaller banks and thus the stability of the banking system. Our analysis proceeds in two steps. In a first step, we follow Gabaix [Gabaix, X., 2008a. The Granular Origins of Aggregate Fluctuations. Available at SSRN: http://ssrn.com/abstract=1111765] and construct a measure of idiosyncratic shocks at large banks, the so-called Banking Granular Residual. This measure documents the importance of size effects for the German banking system. In a second step, we incorporate this measure of idiosyncratic shocks at large banks into an integrated stress-testing model for the German banking system following De Graeve et al. (2008). We find that positive shocks at large banks reduce the probability of distress of small banks.

Financial intermediaries often use stress testing to set risk exposure limits. Accordingly, we examine a model with an agent who faces stress testing constraints and another who does not. Three results are obtained. First, when there are K* binding constraints, the constrained agent's optimal portfolio exhibits (K*+2)-fund separation. Second, the effect of the constraints on the optimal portfolio is identical to that of an adjustment in the expected payoffs of the risky securities that tends to lower them. Third, a security's equilibrium expected return depends on both its systematic risk and its idiosyncratic returns in the states where the constraints bind.

In recent years several companies have offered employees the opportunity to transfer certain out-of-the-money options to a dealer. This paper examines one such high-profile program offered by Microsoft in 2003. The program was not very transparent in that employees were forced to decide whether to tender their options before knowing how much they would be offered, and it had only a modest rate of participation. Nonetheless, the market easily absorbed intense selling pressure as the options were transferred and hedged. The dealer, JPMorgan Chase, though profiting from the transfer, apparently failed to hedge the volatility risk it accepted from the employees and lost nearly the entire value it paid for the options. The overall experience has important implications for the design of programs that are intended to solve problems of low morale and increased turnover caused by underwater options.

ABSTRACT As barriers to international investment fall and technology improves, the cost advantages for a firm's securities to trade publicly in the country in which that firm is located and for that country to have a market for publicly traded securities distinct from the capital markets of other countries will progressively disappear. Securities laws remain an important determinant of whether and where securities are issued, how they are valued, who owns them, and where they trade. I show that there is a demand from entrepreneurs for mechanisms that allow them to commit to credible disclosure because disclosure helps reduce agency costs. Under some circumstances, mandatory disclosure through securities laws can help satisfy that demand, but only provided investors or the state can act on the information disclosed and the laws cannot be weakened ex post too much through lobbying by corporate insiders. With financial globalization, national disclosure laws can have wide‐ranging effects on a country's welfare, on firms and on investor portfolios, including the extent to which share holdings reveal a home bias. In equilibrium, if firms can choose the securities laws they are subject to when they go public, some firms will choose stronger securities laws than those of the country in which they are located and some firms will do the opposite.