Investment banks' stock ratings, call warrant issuance, and responses from heterogeneous investors: Evidence from Taiwan

We investigate the responses of the different types of investors on stock rating change announcements made by investment banks around call warrant issuances in Taiwan. The unique characteristics of the Taiwan warrants market allow investment banks to make stock rating change announcements around call warrant issuances for the same stocks they rate. In Taiwan, investment banks are also dealers of call warrants, and thus, the profit and loss results from their warrant business are potentially in conflict-of-interest for their stock ratings. Another feature of the Taiwan stock market allows us to disentangle the types of investors initiating the stock trades. We identify three types of investors: institutional investors, experienced retail investors, and ordinary retail investors. Our findings suggest that institutional investors are able to “see-through” the conflict-of-interest in investment banks; experienced investors are able to partially “see-through” the conflict-of-interest, and ordinary retail investors are unable to “see-through” the conflict-of-interest of investment banks.