An Anatomy of the Magnet Effect: Evidence from the Korea Stock Exchange High-Frequency Data

We examine the existence and the forms of the magnet effect using transaction files and limit order book of the Korea Stock Exchange. A significant magnet effect exists in all five market microstructure variables (the rate of return, trading volume, volatility, order flow, and order type) when the limit hit becomes imminent. Specifically, investors place increasingly more orders, choose proportionally more market orders, and frequently reposition existing orders to advance transactions. We also find that: (i) a narrower price limit exhibits higher acceleration rates in all five variables compared to a wider price limit; and (ii) the upper limit hits draw heavier volumes of transactions, order submissions and market orders than the lower limit hits. We confirm that the magnet effect is a phenomenon unique only to markets with daily price limit systems.