Services with discriminatory pricing of content by Internet Service Providers (ISPs) have resulted in significant controversy in the recent past, in India and around the world. In our public discourse, conflating discriminatory pricing with net neutrality (technically, non-discriminatory treatment of packets in the network) has added intensity to the debate. However, the effect of such pricing, while still being non-discriminatory in carriage, has not been well understood. This work addresses that gap. We focus on zero rating, a popular model of discriminatory pricing in which a certain basket of `zero-rated' Internet services is made available to customers for free. These zero-rated services are in turn sponsored by payments to the ISP by the corresponding content providers (CPs). We analyse a stylised model with one ISP and two CPs offering comparable content, each of whom can choose to either sponsor or not sponsor their service. The price for the customer and the price of sponsorship is determined by the ISP. Our analysis reveals that zero-rating grants the ISP significant power to `shape' the market in the sense that it can set prices to create content monopolies. This power can be exercised to maximise profits or for other purposes. Indeed, we show that the ISP has an incentive to skew the market, creating a near monopoly for one of the CPs. Interestingly, profit maximisation is achieved through a single `sponsoring price' which can appear to be non-discriminatory.