Insider Trading and Intraday Stock Price Behavior in the Tehran Stock Exchange

Itradayn patterns of trading volume, size, return, and volatility in the Tehran Stock Exchange (TSE) have been investigated using high frequency data from 2008 to 2015.

First, the daily patterns of the four variables namely, trade volume, trade value, price volatility range, and returns in stocks have been investigated using high-frequency data. Then, the role of insider information in formation of the given patterns has been examined.

Our results indicate that trading value and volume follow a J-Shaped pattern , whereas absolute return exhibits an L-Shaped behavior . Our findings are consistent with the existing studies which document an increase in trading value and volume as well as absolute return. However, unlike the existing literature, we do not find a U-Shaped pattern in returns, and no statistically significant difference in returns is found throughout the trading hours. To examine the behavior of informed traders, we examine midsize trades and, consistent with the predictions of Barclay and Warner’s (1993) stealth-trading hypothesis, we find that they have higher price impact compared to other trade sizes. However, our findings do not support the intraday stealth trading pattern, as insiders prefer to trade in low and medium trade size to avoid revealing their information. This may be due to the low liquidity of the TSE.

The findings of this study may show policymakers and planners in the Iranian capital market that halts in the stock market can directly affect traders and increase their transaction risks. Meanwhile, traders who are planning to buy or sell stock in large volumes can use the patterns provided in this paper to understand when the price effect is at its lowest point, and this can help them execute their transactions more efficiently.