We examine a period in Korea during which a price supporting regulation called the putback option was imposed on the IPO underwriter. Under the regulation, individual investors of IPO had put options which can be exercised at 90% of IPO price. We find that during the regulation period, institutional investors’ flipping activity is evident not on the days following the IPO but on the days following the expiration of putback option. Our study shows that the regulation results in merely delaying the institutional investors’ documented trading behavior and provides evidence that the relationship between the underwriter and the institutional investors affects the trading of institutional investors.

我们考察了韩国的一段时期，在这段时期内，对IPO承销商施加了称为回购期权的价格支持法规。根据该规定，首次公开募股的个人投资者持有的认股权可以按首次公开募股价格的90％行使。我们发现，在监管期内，机构投资者的翻转活动不仅在首次公开募股后的几天出现，而且在回购权到期后的几天明显出现。我们的研究表明，该规定仅会延迟机构投资者的书面交易行为，并提供证据表明承销商与机构投资者之间的关系会影响机构投资者的交易。