Some factors might influence initial markup.

Initial Markup is used to establish the sales price; it's indicated in percentage, and the higher that percentage is, the more lucrative the product is. Some factors might influence the initial markup, such as brand, competitors, perceived value, and others. Not paying attention to this can affect the business negatively as it ensures that sales are profitable.

Source: "What Is IMU?" by Matthew Hudson on thebalancesmb.com