The impact of individual investor trading on information asymmetry in the Korean stock market

•Impact of individual investor trading on information asymmetry is studied.•Daily trading volumes of individual investors are considered.•Bid-ask spread is proxied as a level of information asymmetry.•High trading activity by individual investors increases the bid-ask spread.

This paper examines the impact of individual investor trading on information asymmetry in the market. In particular, we examine the relationship between the trading volume by individual investors and the corresponding bid-ask spread in the Korean stock market, where the majority of the trading activity is driven by individual investors and therefore information asymmetry can be evident. We find that high trading activity by individual investors increases the bid-ask spread in a short investment horizon, suggesting that individual investors, as uninformed and unsophisticated traders, amplify the degree of information asymmetry in the market through trading.