PurposeThe purpose of this paper is to examine the ways in which stock market valuation and managerial incentives jointly affect merger and acquisition (M&A) decisions and post‐M&A performance, and to provide new evidence on the agency implications where such acquisitions are driven by the stock market.Design/methodology/approachUtilizing all publicly‐traded US firms in the NYSE, AMEX and NASDAQ during the period from 1992 to 2005 (excluding financial and utility firms), obtained from COMPUSTAT, CRSP, I/B/E/S, and the M&A database provided by SDC Platinum, this paper adopts a two‐stage approach: the first stage, predicts the probability of an M&A based on the market valuation variables; the second stage, regresses the post‐M&A firm performance on the predicted probability of a merger or acquisition from the first stage and other control variables.FindingsMarket valuation has a significant influence on corporate acquisition decisions, particularly for those firms whose compensation packages include less managerial equity ownership, more executive stock options and no long‐term incentive plans, and in those firms where CEOs are serving on the board of directors. The value‐destroying acquisitions made by these types of managers are likely to be financed using the firms' stocks, executed with high premiums and undertaken during periods of high market valuation.Originality/valueThe main finding suggests that market‐driven acquisitions could be value destroying when managers engage in opportunistic acquisitions for reasons of self‐interest. Managerial myopia, overconfidence, misaligned incentives, empire‐building motives and poor corporate governance can all exacerbate the agency problem of market‐driven acquisitions.

Abstract:In this study, we employ a statistical arbitrage approach to demonstrate that momentum investment strategy tend to work better in periods longer than six months, a result different from findings in past literature. Compared with standard parametric tests, the statistical arbitrage method produces more clearly that momentum strategies work only in longer formation and holding periods. Also they yield positive significant returns in an up market, but negative yet insignificant returns in a down market. Disposition and over-confidence effects are important factors contributing to the phenomenon. The over-confidence effect seems to dominate the disposition effect, especially in an up market. Moreover, the over-confidence investment behavior of institutional investors is the main cause for significant momentum returns observed in an up market. In a down market, the institutional investors tend to adopt a contrarian strategy while the individuals are still maintaining momentum behavior within shorter periods. The behavior difference between investor groups explains in part why momentum strategies work differently between up and down market states. Robustness tests confirm that the momentum returns do not come from firm size, overlapping execution periods, market states definition or market frictions.

We analyze in this study what could have caused herding in the stock market. Information cascades have often been considered as a major cause. However, we present in this study evidences inconsistent with that hypothesis. Our analysis is in support of an alternative theory based on search cost of investors. Specifically, previous works studied daily data or those with lower frequency based on a herding measure of Lakonishok, Shleifer, and Vishny (1992). We adopt instead the measure of Patterson and Sharma (2006) and argue that the search model of Vayanos and Wang (2007) characterize herding phenomenon better. Our analysis supports their hypothesis employing intraday order book data. We find that stronger order flow herding is driven by lower transactions cost. Herding tend to occur in trading of high-cap, high turnover stocks, which contradicts prediction of the information cascade hypothesis. Information cascade effect, if any, is actually stronger near market close than at open. Therefore our study suggests that herding could be related more to intrinsic search cost structure of investors rather than information related factors.

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