Kotaro Miwa

The influence of investor's behavioral biases on the usefulness of the Dual Moving Average Crossovers

The so called Dual Moving Average Crossovers are said to be useful signals for forecasting trends of stock prices, as one of the technical analysis methods. First, we examined the usefulness of these crossovers by using historical daily closing price data and tick by tick price data of Japanese stocks. The results revealed that these crossovers were useful as confirmatory signals for forecasting market trends. Second, we tried to identify the underlying reasons for the usefulness of the crossovers. A model, which followed the Efficient Market Hypothesis, was found to fail to generate the price fluctuation where the crossovers were useful. We then developed a model that incorporated investors suspicion about current price validity and two famous behavioral biases: conservativeness and representativeness. We identified the mechanism that those crossovers were closely related to investors suspicion and the behavioral biases.

Is the Extension of Trading Hours Always Beneficial? An Artificial Agent-Based Analysis

The extension of trading hours to provide more trading opportunities and improve price efficiency has increasingly been discussed. However, currently, there is limited trading activity during the stock market’s extended-hours trading session. Thus, we should examine whether the extension of trading hours is still effective for creating more trading opportunity and price efficiency even if there are few market participants during the extended session. For this study, we build an agent-based market model based on that of Brock and Hommes (1998) and analyze the effect of extending trading hours. We find that although extending trading hours could increase daily trading volume, it could distort price formation and trade opportunity if market participants are limited during the extended-hours session. Specifically, the extension could result in more concentrated trading in the opening session, wider divergence between market prices and the fundamental value of stocks, and higher return volatility (especially at the open).

Price Distortion Induced by a Flawed Stock Market Index

Despite the introduction of sophisticated stock market indices, investors often trade portfolios of the flawed indices to change their exposure to the market. In this study, we show that these transactions cause significant mispricing in individual stocks, especially during periods of significant market movement. As an influential, albeit flawed, stock index, we focus on the Nikkei 225. We find index constituents that are excessively weighted on the index, experience buying (selling) pressure when the stock market surges (falls), and experience price corrections after such periods of change. In contrast, non-constituent stocks do not experience such trading pressure.

Effective Trading Hours Extension

To uncover the complex feature of the effect of extending trading hours, I analyze what kind of the extension is effective on price efficiency and price stability, by utilizing an agent-based market model. Specifically, I examine whether the partial extension of trading hours—namely, implementing the pre-market session and the after-hours session—and what duration of the session is effective. The simulation result reveals that the implementation of both sessions could have a negative impact on price efficiency and stability if investors’ participation during the session is limited; it could result in more concentrated trading in the opening session, wider divergence between market prices and the fundamental value, and lower price stability. In addition, longer sessions are less beneficial (or more harmful). My result also shows that there are very few benefits to trade during the extended-hours sessions. Thus, my findings suggest that the extended-hours trading has a structural weakness which causes illiquidity during the session and lowers price efficiency and price stability during the regular-hour session. However, I find that the implementation of the pre-market session is far more beneficial than that of the after-hours session; exceptionally, the implementation of the short-term pre-market session could induce higher price efficiency and higher price stability regardless of the number of market participants during the session.

Analysts’ Preference for Growth Investing and Vulnerability to Market-Wide Sentiment

Existing studies have argued that market-wide sentiment primarily affects individual noise traders, rather than other sophisticated market participants. Contrary to this perspective, in this study, we find that financial analysts, who are sophisticated market participants, may be more vulnerable to sentiment than their peers. As a reason for this vulnerability, we focus on analysts’ preference for growth investing, and predict that, due to this preference, their fair value estimations for growth stocks would be more upwardly biased by bullish market-wide sentiment than those of their market peers. We also predict that this biased estimation for growth stocks would lower the investment value of their recommendations. As is consistent with our predictions, we find that, especially during periods of bullish sentiment, analysts consider growth stocks to be undervalued, even though these stocks are in fact overvalued. In addition, we find that recommended stocks experience poor relative return performance, especially after periods of bullish sentiment, and that this poor performance is not observed after controlling for growth factors.

Stock Futures of a Flawed Market Index

I present evidence that transactions of the stock futures of a flawed market index cause mispricing in individual stocks. In particular, I analyze whether stocks overweighted on the index are mispriced, especially when market movements driven by futures trading are observed. To detect such movements, I use a qualitative indicator based on daily stock market news and a quantitative indicator based on the intraday lead-lag relationship between the spot and futures markets. I find that overweighted stocks are overpriced (underpriced) when upward (downward) movements driven by futures trading are observed. By contrast, such mispricing is not observed for non-constituent stocks.

Slow price reactions to analysts' recommendation revisions

This study explores the reasons for the slow price reactions to analysts’ recommendation revisions. We predict that analysts’ recommendation revisions contain earnings-related information that is not incorporated in analysts’ earnings forecasts and that the slow price reaction is attributable to a gradual incorporation of this earnings-related information into stock prices. We find that, consistent with our prediction, stocks with recommendation upgrades subsequently experience more upward earnings forecast revisions than stocks with recommendation downgrades, and that the differences in subsequent stock returns between upgraded and downgraded stocks is attributable to differences between subsequent earnings forecast (especially, FY2 earnings forecast) revisions.