“…In the baseline model, following the literature (e.g., Boik & Corts,
2016; Johansen & Vergé, 2017; Mariotto & Verdier,
2020), we considered per‐unit platform fees, which allowed to derive simple closed‐form solutions for the equilibrium values. However, in practice, many e‐commerce platforms charge ad‐valorem fees 19 (e.g., Johnson,
2017; Wang & Wright,
2017)—that is,
collects
, with
, for each unit sold by
(at price
) 20…”