Motivated by the increased adoption of autobidding algorithms in internet advertising markets, we study the design of optimal mechanisms for selling items to a value-maximizing buyer with a return-on-spend constraint. The buyer's values and target ratio in the return-on-spend constraint are...

We consider a setting in which potential buyers of an indivisible item have private and heterogeneous valuation and cost of capital. The valuation and cost of capital can be correlated with each other, but they are independent across buyers. In such a setting, a buyer's utility for the item is...