The well-documented volatility smile phenomenon in the US options market has affected the option settlement practices of other markets. To settle Hang Seng Index (HSI) options, the Hong Kong Stock Exchange artificially builds in a piecewise linear “smile” or “sneer” volatility function, which is determined daily by market makers rather than directly by market forces. In this study, we investigate the time-varying settlement function and find the following economic determinants of the volatility function: lag parameters, current-day HSI returns, the distribution of HSI returns, transaction costs as proxied by the bid-ask spread, and the “Monday effect”. For evaluation purposes, we use as a benchmark the estimated piecewise linear volatility function as directly driven by market forces. The comparison analyses show that base volatilities set by market makers run somewhat high, while downside slopes are not steep enough. This results in the overpricing of the lion’s share of traded options. An economic determinants analysis of market-force-driven parameters reveals that market makers can better align artificial volatility parameters both by reducing reliance on the function parameters of prior days and by more precisely accounting for current-day HSI returns, option time-to-maturity, bid-ask spreads and buying pressure.

The past 20 years have seen important changes in public policy with the potential for significant impacts on health insurance for children. These changes included both those explicitly intended to expand access to public insurance for children, including expansions in eligibility for Medicaid and the introduction of the State Children’s Health Insurance Program (SCHIP), and other changes in antipoverty policy. Since health insurance coverage among children is entwined with parental welfare participation and employment, shifts in policy designed to encourage work in place of welfare participation--such as welfare reform and the expansion of the Earned Income Tax Credit (EITC)--may have secondary impacts on children's health insurance coverage. As parents leave welfare, with its guaranteed health insurance through Medicaid, for jobs that may or may not have health insurance coverage offered as a benefit, children may experience a change in the source of their health insurance coverage or may become uninsured. Similarly, changes in health care markets and economic conditions such as rising health care prices and cyclicality in the availability of employment may also affect children's coverage. Despite the potential importance of these factors for coverage, the fraction of children who are uninsured has remained largely constant, particularly through the 1990s. However, this relatively constant level of uninsurance may mask changes in the underlying dynamics of health insurance among children. In this paper, we use monthly data from the 1986–1996 panels of the Survey of Income and Program Participation (SIPP) to examine patterns of health insurance coverage among children during the period 1986–1999, focusing on transitions between public coverage, private coverage, and no coverage. Using these data, we find that over the 1990s the rate of transitions among all three insurance states--public insurance, private insurance, and no insurance--increased, with a particular increase in transitions involving public coverage. We investigate whether there is evidence of a relationship between insurance transitions and various policy and economic variables, focusing on the impacts of expansions in public coverage availability, the effects of other policies directed at the poor that affect employment and insurance coverage, and economic conditions. We find that several of the policy changes that took place over the 1990s had important effects on health insurance transitions for children.

We report evidence on the determinants of whether the relationship between a firm and its Chief Executive Officer (CEO) is governed by an explicit (written) or an implicit agreement. We find that fewer than half of the CEOs of S&P 500 firms have comprehensive explicit employment agreements. Consistent with contracting theory, explicit agreements are more likely to be observed and are likely to have a longer duration in situations in which the sustainability of the relationship is less certain and where the expected loss to the CEO is greater if the firm fails to honor the agreement.

Miller [1977. Risk, uncertainty, and divergence of opinion. Journal of Finance 32, 1151–1168] hypothesizes that prices of stocks subject to high differences of opinion and short-sales constraints are biased upward. We expect earnings announcements to reduce differences of opinion among investors, and consequently, these announcements should reduce overvaluation. Using five distinct proxies for differences of opinion, we find that high differences of opinion stocks earn significantly lower returns around earnings announcements than low differences of opinion stocks. In addition, the returns on high differences of opinion stocks are more negative within the subsample of stocks that are most difficult for investors to sell short. These results are robust when we control for the size effect and the market-to-book effect and when we examine alternative explanations such as financial leverage, earnings announcement premium, post-earnings announcement drift, return momentum, and potential biases in analysts’ forecasts. Also consistent with Miller's theory, we find that stocks subject to high differences of opinion and more binding short-sales constraints have a price run-up just prior to earnings announcements that is followed by an even larger decline after the announcements.

Regulations allow market makers to short sell without borrowing stock, and the transactions of a major options market maker show that in most hard-to-borrow situations, it chooses not to borrow and instead fails to deliver stock to its buyers. A part of the value of failing passes through to options prices: when failing is cheaper than borrowing, the relation between borrowing costs and options prices is significantly weaker. The remaining value is profit to the market maker, and its ability to profit despite competition between market makers appears to result from the cost advantage of larger market makers.

While many technical trading rules are based upon patterns in asset prices, we lack convincing explanations of how and why these patterns arise, and why trading rules based on technical analysis are profitable. This paper provides a model that explains the success of certain trading rules that are based on patterns in past prices. We point to the importance of confirmation bias, which has been shown to play a key role in other types of decision making. Traders who acquire information and trade on the basis of that information tend to bias their interpretation of subsequent information in the direction of their original view. This produces autocorrelations and patterns of price movement that can predict future prices, such as the “head-and-shoulders” and “double-top” patterns. The model also predicts that sequential price jumps for a particular stock will be positively autocorrelated. We test this prediction and find that jumps exhibit statistically and economically significant positive autocorrelations.

We find that corporate governance characteristics of acquiring firms (board ownership, board size, and block-holder control) have an economically and statistically significant impact on operating performance changes following mergers. We also show that dispersion of intra-board ownership stakes is an important but heretofore overlooked factor when judging the influence of ownership on the outcomes of corporate choices. Finally, we present evidence that suggests the market sometimes under- or overreacts to merger news when initially revaluing merger partners but corrects any miscalculation following the consummation of the merger.

There is much recent interest in the role of market timing in firm financial decisions. Using a large detailed sample of corporate public debt issues, private placements, Rule 144A issues and bank loans over the period 1970–2006, we investigate the relationship between interest rate changes and issues of floating and fixed-rate debt. Our results indicate that both past and future rates are associated with issuance decisions. We examine whether firms are able to lower their cost of capital by anticipating future rate changes, controlling for firm characteristics and market conditions. Our findings suggest that evidence of timing success is dependent on the time interval and type of debt examined. Over the longest time intervals available in our data, we do not find evidence of timing ability for fixed-rate or floating-rate debt issues.

We show that individual investors over-extrapolate from their personal experience when making savings decisions. Investors who experience particularly rewarding outcomes from 401(k) saving—a high average and/or low variance return—increase their 401(k) savings rate more than investors who have less rewarding experiences. This finding is not driven by aggregate time-series shocks, income effects, rational learning about investing skill, investor fixed effects, or time-varying investor-level heterogeneity that is correlated with portfolio allocations to stock, bond, and cash asset classes. We discuss implications for the equity premium puzzle and interventions aimed at improving household financial outcomes.

Stem cell transplants save lives of many patients with blood diseases. Donation is painful, but rarely has lasting adverse effects. Patients can accept transplants only from donors with compatible immune systems. Those lacking a sibling match must seek donations from the general population. The probability that two unrelated persons are compatible is less than 1/10,000. Health authorities maintain a registry of several million genetically tested potential donors who agree to donate if asked. We find that the benefits of adding registrants of every race exceed costs. We also explore the peculiar structure of voluntary public good provision that faces potential donors.