Before revision:  In many such platforms prices are set by revenue-maximizing sellers, but the platform may influence prices through its promotion policy (e.g., increasing demand to a certain product by assigning to it a prominent position on the webpage ), and the information it reveals about the additional demand associated with being promoted.
After revision:  In many such platforms prices are set by revenue-maximizing sellers, but the platform may influence prices through (i) price-dependent promotion policies that can increase demand for a product by featuring it in a prominent position on the webpage ), and the information it reveals about the additional demand associated with being promoted.