How do sponsored advertisements affect product market concentration, through their effects on firms' pricing and consumer behaviour? To analyse this, I develop a theory of digital markets where an intermediary provides a platform for firms to advertise their product and where consumers need to engage in costly search if they want to learn about the product characteristics. First, I show that when prices are observable prior to the costly product inspection, the less prominent (lower in the search order) firm is forced to lower its price in order to attract more visitors, thus putting it at a competitive disadvantage. Second, I augment this model by allowing the intermediary to determine endogenously, through an auction, the order in which products are displayed and the advertising commissions to be paid (per-click). I show that the pass-through from these commissions to product prices is actually higher for the less prominent firm, thus further putting it at a competitive disadvantage. In equilibrium, these asymmetries in consumer price elasticity and commission pass-through lead to lower competition, consumer surplus and total transactions in the product market. Third, I show that the pay per- click business model is intermediary-optimal while the pay per-sale and the consumer subscription fee models improve consumer surplus at the expense of the intermediary. Fourth, I provide novel empirical evidence that is consistent with some key predictions of the model. These results contribute to the ongoing policy discussions on the effect of dominant digital platforms on product market concentration.

 Does the environment of politicians affect their collaboration with firms? We address this question using unique data on the speeches of U.S. legislators and their lobbying by foreign organizations. We find that when external events tarnish a country's reputation, the average U.S. legislator provides lower political support to entities located in that country (less enthusiastic speeches) at a higher price (more intense lobbying effort). This average adjustment, however, masks important differences across politicians: the observed patterns are driven by legislators who have prior connections to the shocked country, and who come from states with strong political competition and where citizens have a negative view of that country. Our results suggest that firms' collaborations with politicians are not homogeneous, and are shaped by the punishment risk coming from each politician's local stakeholders.

 This paper examines the impact of caste norms on product demand, firm size and real income in rural India. First, we establish changes in regional rainfall intensity as an asymmetric demand-shifter to members of different castes. Specifically, when consumers from Low-rank castes (LC) experience a positive shift in income due to good rainfall, relative to others, they increase their spending across various non-agricultural product categories, whose supply is not directly affected by rainfall. Second, we use novel data on the caste of firm owners and the caste composition of employees within a firm to document that the increase in LC households' demand leads to higher growth for the firms owned by members of the same caste category, relative to others. Motivated by these empirical findings, we develop a framework where firms sell products across castes, and consumers' taste for products depends on the quality and the caste of the producer. And in response, firms invest to influence the consumer's taste by hiring workers from the target consumers' caste. The model highlights that caste-specificity in product taste lowers cross-caste sales, lowers firm size, raises the proportion of small firms, and lowers real income.

 Tanto en EE. UU. como en España, la publicidad online ya supuso en 2021 más del 50 por 100 del gasto total en publicidad. Unido a múltiples retos ya conocidos por los economistas (barreras de entrada por economías de escala, switching costs, efectos de red), la publicidad online añade además la personalización de la publicidad y las dificultades para preservar la privacidad. Veremos que la publicidad online potencialmente puede tanto favorecer como dificultar la competencia. Repasaremos literatura académica que ofrece claves para identificar y cuantificar formas en que la publicidad online puede generar barreras a la competencia y daños a los consumidores.

 - The Turing Way's guide to reproducible research
   - Tools for Empirical research
   - Tips for Economists

 - Watch: Shoplifters, (2018) - Japan
   - Read: The Paper Menagerie, by Ken Liu

 - night comes first (ongoing): முதலில் இரவு வரும் - ஆதவன், 1985 (Tamil)