Jerold B. Warner

Using daily stock returns: The case of event studies☆

This paper examines properties of daily stock returns and how the particular characteristics of these data affect event study methodologies. Daily data generally present few difficulties for event studies. Standard procedures are typically well-specified even when special daily data characteristics are ignored. However, recognition of autocorrelation in daily excess returns and changes in their variance conditional on an event can sometimes be advantageous. In addition, tests ignoring cross-sectional dependence can be well-specified and have higher power than tests which account for potential dependence.

MEASURING SECURITY PRICE PERFORMANCE

Event studies focus on the impact of particular types of firm-specific events on the prices of the affected firms’ securities. In this paper, observed stock return data are employed to examine various methodologies which are used 111 event studies to measure security price performance. Abnormal performance is Introduced into this data. We find that a simple methodology based on the market model performs well under a wide variety of conditions. In some situations, even simpler methods which do not explicitly adjust for marketwide factors or for risk perform no worse than the market model. We also show how misuse of any of the methodologies can result in false inferences about the presence of abnormal performance.

On financial contracting: An analysis of bond covenants

Abstract With risky debt outstanding, stockholder actions aimed at maximizing the value of their equity claim can result in a reduction in the value of both the firm and its outstanding bonds. We examine ways in which debt contracts are written to control the conflict between bondholders and stockholders. We find that extensive direct restrictions on production/investment policy would be expensive to employ and are not observed. However, dividend and financing policy restrictions are written to give stockholders incentives to follow a firm-value-maximizing production/investment policy. Taking into account how contracts control the bondholder- stockholder conflict leads to a number of testable propositions about the specific form of the debt contract that a firm will choose.

Stock Prices and Top Management Changes

This paper studies the association between a firms stock returns and subsequent top management changes. Consistent with internal monitoring of management, there is an inverse relation between the probability of a management change and a firms share performance. This relation can result from monitoring by the board, other top managers, or blockholders. However, unless share performance is extremely good or bad, logit models have no predictive ability. No average stock reaction is detected at announcement of a top management change.

Measuring Long-Horizon Security Price Performance

This paper studies the specification of tests for long-horizon (i.e., multiyear) abnormal security returns around firm-specific events, using samples of randomly selected securities and simulated event dates. The main result is that typical long-horizon tests are misspecified. The tests have a severe tendency to indicate abnormal performance when none is present, with rejection frequencies sometimes exceeding 5 to 10 times the significance level of the test. The result is not sensitive to the specific model used for estimating abnormal returns. The parametric test statistics do not satisfy their assumed properties. We identify several sources of misspecification.

Econometrics of Event Studies

Abstract The number of published event studies exceeds 500, and the literature continues to grow. We provide an overview of event study methods. Short-horizon methods are quite reliable. While long-horizon methods have improved, serious limitations remain. A challenge is to continue to refine long-horizon methods. We present new evidence illustrating that properties of event study methods can vary by calendar time period and can depend on event sample firm characteristics such as volatility. This reinforces the importance of using stratified samples to examine event study statistical properties.

The Distribution of Power Among Corporate Managers, Shareholders, and Directors

This article surveys the seventeen papers in this special issue of the Journal of Financial Economics, and related work. The major findings are: (1) patterns of stock ownership by insiders and outsiders can influence managerial behavior, corporate performance, and stockholder voting in election contests; (2) corporate leverage, inside stock ownership by managers, and the control market are interrelated; (3) departures from one share/one vote affect firm value and efficiency; (4) takeover resistance through defensive restructurings or poison pill provisions is associated with declines in share price; and (5) top management turnover is inversely related to share price performance.

Aggregate Price Effects of Institutional Trading: A Study of Mutual Fund Flow and Market Returns

We study the relation between market returns and aggregate flow into U.S. equity funds, using daily flow data. The concurrent daily relation is positive. Our tests show that this concurrent relation reflects flow and institutional trading affecting returns. This daily relation is similar in magnitude to the price impact reported for an individual institutions trades in a stock. Aggregate flow also follows market returns with a one-day lag. The lagged response of flow suggests either a common response of both returns and flow to new information, or positive feedback trading.

Stock Returns, Aggregate Earnings Surprises, and Behavioral Finance

We study the stock market reaction to aggregate earnings news. Previous research shows that, for individual firms, stock prices react positively to earnings news but require several quarters to fully reflect the information in earnings. We find that the relation between returns and earnings is substantially different in aggregate data. First, returns are unrelated to past earnings, suggesting that prices neither underreact nor overreact to aggregate earnings news. Second, aggregate returns are negatively correlated with concurrent earnings; over the last 30 years, stock prices increased 6.5% in quarters with negative earnings growth and only 1.9% otherwise. This finding suggests that earnings and discount rates move together over time, and provides new evidence that discount-rate shocks explain a significant fraction of aggregate stock returns.

Bankruptcy, absolute priority, and the pricing of risky debt claims

Abstract In practice, there are substantial deviations from the doctrine of ‘absolute priority’, which governs the rights of the firms claimholders in the event of bankruptcy. To determine whether or not the possibility of such deviations is reflected in the prices of the firms securities, this study examines the risk and return characteristics of financial claims against firms in court-supervised bankruptcy proceedings. Debt claims against bankrupt firms are indeed ‘risky’, exhibiting levels of systematic risk similar to that of common stocks in general. While some of the findings are anomalous, the data are generally consistent with the view that the capital market ‘properly’ prices risky debt claims to reflect both their risk characteristics and the possibility of departures from the doctrine of absolute priority.