A key issue gaining attention in the field of entrepreneurship is answering the question of who will appropriate the rents associated with entrepreneurial activity. While entrepreneurs may expend substantial resources to pursue an opportunity, others may be able to appropriate value if the entrepreneurs have not established protections. For example, a key supplier who provides a critical input into the entrepreneur’s product may be able to negotiate for higher prices over time. As such, the decision to utilize a market transaction poses hazards for the entrepreneurial firm. In this paper we specifically examine a situation where IPO firms are dependent on a key transaction partner. We examine the stock price of these transaction partners to examine whether they enjoy a cumulative abnormal return (CAR) in stock price when the dependent IPO firm registers its first S-1 form (which is the preliminary prospectus) with the SEC. Furthermore, we examine whether the size of the IPO firm has a positive impact on this CAR.