Each share splits the sold total by the pins' calculated prices, so a pricier pin carries more of it.
Sold is the marketplace's own record: Mercari's sold listings, and eBay's count of units sold on a listing we tracked. Probably sold is inferred: an eBay listing that ended before we could ask eBay about it, and disappeared and stayed gone — except one that ended exactly at the end of a listing period (7 days, or a multiple of 30), which most likely just was not relisted — or a drop in Pinny Shop's stock, at that day's price. A sale in a lot is several pins sold for one price; this pin's share splits it by the pins' calculated prices, and it is not counted in the calculated price.