Franklin Allen

Using genetic algorithms to find technical trading rules

A genetic algorithm is used to learn technical trading rules for Standard and Poors composite stock index using data from 1963-69. In the out-of-sample test period 1970-1989 the rules are able to identify periods to be in the indexwhen returns are positive and volatility is low and out when the reverse is true. Compared to a simple buy-and-hold strategy, they lead to positive excess returns after transaction costs in the period of 1970-89. Using data for other periods since 1929, the rules can identify high returns and low volatility but do not lead to excess returns after transaction costs. The results are compared to benchmark models of a random walk, an autoregressive model, and a GARCH-AR model. Bootstrapping simulations indicate that none of these models of stock returns can explain the findings.

Bubbles and Crises

In recent financial crises a bubble, in which asset prices rise, is followed by a collapse and widespread default. Bubbles are caused by agency relationships in the banking sector. Investors use money borrowed from banks to invest in risky assets, which are relatively attractive because investors can avoid losses in low payoff states by defaulting on the loan. This risk shifting leads investors to bid up the asset prices. Risk can originate in both the real and financial sectors. Financial fragility occurs when positive credit expansion is insufficient to prevent a crisis.

Competition and Financial Stability

Competition policy in the banking sector is complicated by the necessity of maintaining financial stability. Greater competition may be good for (static) efficiency, but bad for financial stability. From the point of view of welfare economics, the relevant question is: what are the efficient levels of competition and financial stability? We use a variety of models to address this question and find that different models provide different answers. The relationship between competition and stability is complex: sometimes competition increases stability. In addition, in a second-best world, concentration may be socially preferable to perfect competition and perfect stability may be socially undesirable.

The Theory of Financial Intermediation

Traditional theories of intermediation are based on transaction costs and asymmetric information. They are designed to account for institutions which take deposits or issue insurance policies and channel funds to firms. However, in recent decades there have been significant changes. Although transaction costs and asymmetric information have declined, intermediation has increased. New markets for financial futures and options are mainly markets for intermediaries rather than individuals or firms. These changes are difficult to reconcile with the traditional theories. We discuss the role of intermediation in this new context stressing risk trading and participation costs.

Reputation and Product Quality

This article considers the role of reputation in a competitive market where product quality is unobservable. It is shown, among other things, that there can exist equilibria where price is equal to average cost but greater than marginal cost. No. firm cuts its price because this would make it more profitable to produce low- rather than high-quality goods; consumers are aware of this and would not buy its products.

Financial Markets, Intermediaries, and Intertemporal Smoothing

In an overlapping generations economy with (incomplete) financial markets but no intermediaries, there is underinvestment in safe assets. In an economy with intermediaries and no financial markets, accumulating reserves of safe assets allows returns to be smoothed, nondiversifiable risk to be eliminated, and an ex ante Pareto improvement compared to the allocation in the market equilibrium to be achieved. In a mixed financial system, however, competition from financial markets constrains intermediaries so that they perform no better than markets alone.

What do financial intermediaries do

This paper presents evidence that the traditional banking business of accepting deposits and making loans has declined significantly in the US in recent years. There has been a switch from directly held assets to pension funds and mutual funds. However, banks have maintained their position relative to GDP by innovating and switching from their traditional business to fee-producing activities. A comparison of investor portfolios across countries shows that households in the US and UK bear considerably more risk from their investments than counterparts in Japan, France and Germany. It is argued that in these latter countries intermediaries can manage risk by holding liquid reserves and intertemporally smoothing. However, in the US and UK competition from financial markets prevents this and risk management must be accomplished using derivatives and other similar techniques. The decline in the traditional banking business and the financial innovation undertaken by banks in the US is interpreted as a response to the competition from markets and the decline of intertemporal smoothing.

The market for information and the origin of financial intermediation

Abstract When information is sold, there is often a reliability problem since anyone can claim to have superior knowledge. Optimal strategies which allow a seller to establish that he is informed are considered in a standard one-period, two-asset model. When risk aversion is unobservable, an information market is viable and both the seller and the buyers are better off participating. However, the seller cannot obtain the full value of his information because of the reliability problem. This provides an opportunity for intermediation since an intermediary may be able to capture some of the remaining value.

A welfare comparison of intermediaries and financial markets in Germany and the US

Abstract There is wide variation in the structures of financial systems in different countries. We compare two polar extremes. In one, which we refer to as the ‘German model’, intermediaries predominate. In the second, which we refer to as the ‘U.S. model’, financial markets play the major role. Our objective is to contribute to a theoretical framework for the welfare analysis of comparative financial systems. The study is divided into two parts, which focus on financial services provided to households and firms, respectively. On the household side, we consider issues such as cross-sectional and intertemporal risk sharing, noise suppression and the provision of services. On the firm side, we consider information, financing, the market for corporate control, and diversity of opinion.

Networks in Finance

Modern financial systems exhibit a high degree of interdependence. There are different possible sources of connections between financial institutions, stemming from both the asset and the liability side of their balance sheet. For instance, banks are directly connected through mutual exposures acquired on the interbank market. Likewise, holding similar portfolios or sharing the same mass of depositors creates indirect linkages between financial institutions. Broadly understood as a collection of nodes and links between nodes, networks can be a useful representation of financial systems. By providing means to model the specifics of economic interactions, network analysis can better explain certain economic phenomena. In this paper we argue that the use of network theories can enrich our understanding of financial systems. We review the recent developments in financial networks, highlighting the synergies created from applying network theory to answer financial questions. Further, we propose several directions of research. First, we consider the issue of systemic risk. In this context, two questions arise: how resilient financial networks are to contagion, and how financial institutions form connections when exposed to the risk of contagion. The second issue we consider is how network theory can be used to explain freezes in the interbank market of the type we have observed in August 2007 and subsequently. The third issue is how social networks can improve investment decisions and corporate governance. Recent empirical work has provided some interesting results in this regard. The fourth issue concerns the role of networks in distributing primary issues of securities as, for example, in initial public offerings, or seasoned debt and equity issues. Finally, we consider the role of networks as a form of mutual monitoring as in microfinance.