SPECULATION AND THE MARKET FOR RECOMMENDATIONS

The purpose of this paper is to investigate the theoretical value of information in a speculative securities market. A model of speculative equilibrium is developed in a market where an independent profit-seeking advisor sells information in the form of buy and sell recommendations. These recommendations and the record of the advisor determine traders' speculative commitments, which take explicit account of informational risk. The model leads to a complete specification of the speculative equilibrium which includes stock prices as well as the price that the advisor can charge for providing recommendations.     

Accounting for Risk and Return in Equity Valuation

Standard valuation models forecast cash flows or earnings, add a growth rate, and discount the cash flows to their present value with a discount rate that typically reflects the cost of capital. But as the author argues, projecting the long‐term growth rate is essentially speculative; and along with uncertainty about the growth rate, analysts generally do not have a good grasp of the discount rate either. Thus, instead of reducing uncertainty, these two features effectively compound uncertainty in valuations in the sense that slight changes in the growth rate or discount rate can change the valuation considerably. In this article, the author proposes an alternative approach that views the investor's problem as one of challenging the speculations that are built into the current market price, particularly the speculation about growth. Rather than building in a speculative growth rate (and thereby treating it as if it were a certainty), the author's approach turns the problem on its head by using an accounting analysis of the firm's current earnings and cash flows that provides a basis for recognizing the speculative component of the current stock price. More specifically, the author's analysis identifies the future earnings growth path that is implied by the market price, which can then be evaluated with the question: Do I want to pay for this growth? Because growth expectations are risky, additional analysis can be used to provide an understanding of the risk and return to buying growth, and of the upside and downside if risk growth expectations are not realized. By taking such an approach, investors incorporate their understanding of risk not by increasing the discount rate, but by recognizing that the primary risk in investing is the risk of overpaying for growth.     

Equilibrium Exchange Rate Hedging

We assume a world like the one that gives the capital asset pricing model, but with many goods and many countries. We assume that investors in a given country have homothetic utility functions with the same weights, and a currency that has a sure end-of-period value using a price index with those weights. Siegel's paradox (derived from Jensen's inequality) makes investors want a positive amount of exchange risk. When average risk tolerance is the same across countries, every investor will hold the same mix of market risk (through the world market portfolio of all assets) and exchange risk (in a diversified basket of foreign currencies). In fact, the ratio of exchange risk to market risk is equal to the average investor's risk tolerance. We can write the ratio of exchange risk to market risk (and the fraction of the market's exchange risk that investors hedge) as depending on an average of world market risk premia, an average of world market volatilities, and an average of exchange rate volatilities. The weights in these averages are the same as the weights of the different countries in the currency basket. Given these averages, the ratio (and the fraction hedged) will not depend directly on exchange rate means or covariances. In equilibrium, we can use the ratio of exchange risk to market risk to measure average risk tolerance: in this model, risk tolerance is observable.     

The Opportunity Cost of a Mean-Variance Efficient Choice

The mean-variance criterion is one of the most frequently used methods for selecting investment portfolios. Yet, because it is an approximation of an investor's maximum expected utility choice, some theoreticians and practitioners have criticized the approach. This paper examines the investment loss that different investors experience by accepting a mean-variance efficient portfolio. Simulated security returns with extreme distributional characteristics are used to determine the extent of an investor's loss. The results indicate that even under very unreasonable investment distributional assumptions, an investor's loss by accepting a mean-variance efficient choice rarely exceeds a small fraction of one percent per invested dollar.     

Optimal mean-reversion strategy in the presence of bid-ask spread and delays in capital allocations

A portfolio optimization problem for an investor who trades T-bills and a mean-reverting stock in the presence of proportional and convex transaction costs is considered. The proportional transaction cost represents a bid-ask spread, while the convex transaction cost is used to model delays in capital allocations. I utilize the historical bid-ask spread in US stock market and assume that the stock reverts on yearly basis, while an investor follows monthly changes in the stock price. It is found that proportional transaction cost has a relatively weak effect on the expected return and the Sharpe ratio of the investor's portfolio. Meantime, the presence of delays in capital allocations has a dramatic impact on the expected return and the Sharpe ratio of the investor's portfolio. I also find the robust optimal strategy in the presence of model uncertainty and show that the latter increases the effective risk aversion of the investor and makes her view the stock as more risky.     

The curse of knowledge: having access to customer information can reduce monopoly profits

We show that a monopolist's profit is higher if he refrains from collecting coarse information on his customers, sticking to constant uniform pricing rather than recognizing customers' segments through their purchase history. In the Markov perfect equilibrium with coarse information collection, after each commitment period, a new introductory price is offered to attract new customers, creating a new market segment for price discrimination. Eventually, the whole market is covered. Shortening the commitment period results in lower profits. These results sharply differ from the ones obtained when the firm can uncover the exact willingness-to-pay of each previous customer.     

Optimal market making in the presence of latency

This paper studies optimal market making for large-tick assets in the presence of latency. We consider a random walk model for the asset price and formulate the market maker's optimization problem using Markov Decision Processes (MDP). We characterize the value of an order and show that it plays the role of one-period reward in the MDP model. Based on this characterization, we provide explicit criteria for assessing the profitability of market making when there is latency. Under our model, we show that a market maker can earn a positive expected profit if there are sufficient uninformed market orders hitting the market maker's limit orders compared with the rate of price jumps, and the trading horizon is sufficiently long. In addition, our theoretical and numerical results suggest that latency can be an additional source of risk and latency impacts negatively the performance of market makers.     

The implied Sharpe ratio

In an incomplete market, including liquidly traded European options in an investment portfolio could potentially improve the expected terminal utility for a risk-averse investor. However, unlike the Sharpe ratio, which provides a concise measure of the relative investment attractiveness of different underlying risky assets, there is no such measure available to help investors choose among the different European options. We introduce a new concept—the implied Sharpe ratio—which allows investors to make such a comparison in an incomplete financial market. Specifically, when comparing various European options, it is the option with the highest implied Sharpe ratio that, if included in an investor's portfolio, will improve his expected utility the most. Through the method of Taylor series expansion of the state-dependent coefficients in a nonlinear partial differential equation, we also establish the behaviour of the implied Sharpe ratio with respect to an investor's risk-aversion parameter. In a series of numerical studies, we compare the investment attractiveness of different European options by studying their implied Sharpe ratio.     

Profit sharing (with workers) facilitates collusion (among firms)

We show how profit sharing by firms with workers facilitates collusion among firms in a dynamic oligopoly environment with uncertain demand. We first show that firm profits can always be increased by tying wages to market conditions. The optimal agreement takes the form of an option and features partial sharing because increased sharing raises the expected price‐wage differential, but reduces price‐wage variability. We then show that given any cartel, there exist market conditions such that simply giving some expected profit to workers raises expected firm profits via the transfer's impact on the incentive to cheat on the cartel.     

Strategic execution in the presence of an uninformed arbitrageur

We consider a trader who aims to liquidate a large position in the presence of an arbitrageur who hopes to profit from the trader's activity. The arbitrageur is uncertain about the trader's position and learns from observed price fluctuations. This is a dynamic game with asymmetric information. We present an algorithm for computing perfect Bayesian equilibrium behavior and conduct numerical experiments. Our results demonstrate that the trader's strategy differs significantly from one that would be optimal in the absence of the arbitrageur. In particular, the trader must balance the conflicting desires of minimizing price impact and minimizing information that is signaled through trading. Accounting for information signaling and the presence of strategic adversaries can greatly reduce execution costs.     

Price Clustering in the U.S. Dollar/Taiwan Dollar Swap Market

Price clustering in financial markets is pervasive. Using transaction‐level data from the world's largest financial market, this study is the first to examine price clustering behavior in the foreign exchange swap market. In addition to existing hypotheses, we investigate new determinants of price clustering including the expected return, contract liquidity, and trader's identity. The results support both negotiation and price resolution hypotheses. We find a positive effect from the level of expected return on price clustering. Markets with greater liquidity experience reduced clustering. Transactions involving domestic banks have less clustering suggesting an information advantage over foreign banks.     

Reliability-Relevance Trade-Offs and the Efficiency of Aggregation

This paper studies how an accountant's method of aggregating information in a financial report is affected by differences in the reliability and relevance of components of the report. We study a firm that hires an accountant to produce a report that reveals information to investors regarding the returns to the firm's past investments. In constructing the report, the accountant must combine information elicited from the firm's manager with other information directly observable to the accountant. The manager's information is assumed to be directly observable only by the manager and to be of superior quality to the other information available to the accountant. Reliability‐relevance trade‐offs arise because as the accountant places more weight on the manager's report, potentially more useful information gets included in the report, at the cost of encouraging the manager to distort his or her information to a greater extent. Capital market participants anticipate this behavior and price the firm accordingly. We show how the market's price response to the release of the firm's aggregate report, the efficiency of the firm's investment decisions, and the manager's incentives to manipulate the soft information under his or her control are all affected by—and affect—the aggregation procedure the accountant adopts. In addition, we identify a broad range of circumstances under which aggregated reports are strictly more efficient than disaggregated reports because aggregation tempers the manager's misreporting incentives. We also demonstrate that, as any given component of the aggregated accounting report becomes softer, the equilibrium level of the firm's investment diminishes and the market places greater weight on the remaining components of the report.     

Stock Market Efficiency and Economic Efficiency: Is There a Connection?

In a capitalist economy, prices serve to equilibrate supply and demand for goods and services, continually changing to reallocate resources to their most efficient uses. However, secondary stock market prices, often viewed as the most “informationally efficient” prices in the economy, have no direct role in the allocation of equity capital since managers have discretion in determining the level of investment. What is the link between stock price informational efficiency and economic efficiency? We present a model of the stock market in which: (i) managers have discretion in making investments and must be given the right incentives; and (ii) stock market traders may have important information that managers do not have about the value of prospective investment opportunities. In equilibrium, information in stock prices will guide investment decisions because managers will be compensated based on informative stock prices in the future. The stock market indirectly guides investment by transferring two kinds of information: information about investment opportunities and information about managers' past decisions. However, because this role is only indirect, the link between price efficiency and economic efficiency is tenuous. We show that stock price efficiency is not sufficient for economic efficiency by showing that the model may have another equilibrium in which prices are strong-form efficient, but investment decisions are suboptimal. We also suggest that stock market efficiency is not necessary for investment efficiency by considering a banking system that can serve as an alternative institution for the efficient allocation of investment resources.     

A Bayesian's Bubble

The acceleration of the U.S. productivity growth in the late 1990s suggests a significant advance in technological innovation, making the perceived probability of entering a “new economy” ever increasing. Based on macroeconomic data, we identify a Bayesian investor's belief evolution when facing a possible structural break in the economy. We show that such belief evolution plays a significant role in explaining both the stock market boom and crash during 1998 to 2001. We conclude that a rational investor's uncertainty about the future of the U.S. economy provides an alternative explanation for the late 1990s stock market “bubble.”     

Convex risk measures based on generalized lower deviation and their applications

Considering the implementability and the properties that a reasonable and realistic risk measure should satisfy, we propose a new class of risk measures based on generalized lower deviation with respect to a chosen benchmark. Besides convexity and monotonicity, our new risk measure can reflect the investor's degree of risk aversion as well as the fat-tail phenomenon of the loss distribution with the help of different benchmarks and weighted functions. Based on the new risk measure, we establish a realistic portfolio selection model taking market frictions into account. To examine the influence of the benchmarks and weighted functions on the optimal portfolio and its performance, we carry out a series of empirical studies in Chinese stock markets. Our in-sample and out-of-sample results show that the new risk measure and the corresponding portfolio selection model can reflect the investor's risk averse attitude and the impact of different trading constraints. Most importantly, with the new risk measure we can obtain an optimal portfolio which is more robust and superior to the optimal portfolios obtained with the traditional expected shortfall risk measures.     

On Viable Diffusion Price Processes of the Market Portfolio

The assumption that the market portfolio follows a specified diffusion process implies, in a simple equilibrium framework, that the representative individual must have a certain utility function which is identified in the paper. Not every diffusion process is viable, i.e., can be “endogenized” to be the market portfolio's price process in such an equilibrium model. The paper provides necessary and sufficient conditions for viability which imply that viable diffusion processes constitute a rather restricted family.     

Money Doctors

We present a new model of investors delegating portfolio management to professionals based on trust. Trust in the manager reduces an investor's perception of the riskiness of a given investment, and allows managers to charge fees. Money managers compete for investor funds by setting fees, but because of trust, fees do not fall to costs. In equilibrium, fees are higher for assets with higher expected return, managers on average underperform the market net of fees, but investors nevertheless prefer to hire managers to investing on their own. When investors hold biased expectations, trust causes managers to pander to investor beliefs.     

Correlated Trading and Returns

A German broker's clients place similar speculative trades and therefore tend to be on the same side of the market in a given stock during a given day, week, month, and quarter. Aggregate liquidity effects, short sale constraints, the systematic execution of limit orders (coordinated through price movements) or the correlated trading of other investors who pick off retail limit orders do not fully explain why retail investors trade similarly. Correlated market orders lead returns, presumably due to persistent speculative price pressure. Correlated limit orders also predict subsequent returns, consistent with executed limit orders being compensated for accommodating liquidity demands.     

The Traditional Hedging Model Revisited with a Nonobservable Convenience Yield

This article examines the hedging of constrained commodity positions with futures contracts. We extend the study of Adler and Detemple (1988a, 1988b) to include a partial information framework where the convenience yield is not observable. As a consequence, futures prices depend on investor's beliefs regarding the value of the convenience yield, and every component of the hedge is impacted by these beliefs. We achieve a decomposition of the demand that clarifies the impact on the optimal hedge of the beliefs, the spot price and the risk‐free rate as well as the hedging horizon.