Panagiotis Kyriazis

How should consumers learn when a seller chooses a menu of product qualities and prices? We study information design when the seller observes the learning policy, but not consumers' private signals, before choosing its menu. Under cost-curvature conditions, we characterize optimal learning when consumer surplus receives greater weight than profit. Even with two valuations, every optimal posterior distribution combines an interval of posterior types with an efficiently served atom at the highest valuation. The induced menu features a continuum of differentiated products. Strikingly, optimal learning can also induce a lower posterior atom, separated from this interval by a support gap. Buyers in this atom either purchase an isolated low-quality product or are excluded, even when trade with every buyer creates gains. Both configurations can be optimal for the same prior and welfare weight. Served buyers with distinct posterior types are never bunched at the same quality. General finite priors can yield several separating regions and trading atoms. We also characterize the optimal joint design of learning and valuation-dependent segmentation, showing, among other results, that every posterior type with positive gains from trade must be served. Joint design can raise both consumer surplus and profit relative to buyer-optimal private learning alone. Even random assignment to segments with different learning policies and separate menus can give consumers more surplus than any single market yielding the same profit. Additional price discrimination can therefore benefit consumers, even when privacy restrictions require segmentation to reveal nothing about valuations to the seller.

We characterize the structure of market compositions that generate Pareto efficient outcomes and the geometry of the surplus set in a screening model with type-dependent costs. Maximizing principal or total surplus concentrates the market at the highest type, with all surplus extracted. Agent-oriented optima instead use, rather than suppress, screening: all agents in the market are served, there is no bunching, and a positive share of agents have the highest type and are served efficiently. Separation is valuable even under agent surplus maximization because it propagates information rents. Under a mild cost-curvature condition, each Pareto efficient outcome is implemented by a unique market. Under a stronger cost-curvature condition, the surplus set is convex whenever values are private, or types with no gains from trade can be included in the market. We characterize all surplus outcomes in these cases. Without such types and with type-dependent costs, the surplus set can be nonconvex. Market segmentation generates the missing outcomes but does not increase the maximum agent surplus at any level of principal surplus. We also derive comparative statics along the Pareto frontier and with respect to value-cost co-movement, distinguishing changes in market composition from changes in individual allocations and rents.

We study exclusive ownership of an input that lowers the cost of quality provision. Two firms first compete for exclusivity and then compete in quality and prices in a covered discrete-choice market. We derive existence conditions for the quality–price equilibrium under non-exclusivity and exclusivity, and show exclusivity is the unique equilibrium outcome. Compared to non-exclusive access, the excluded firm offers lower quality and price, reducing net utility, while the exclusive owner raises both; with sufficiently weak downstream competition, price rises more than quality (pass-through above one), so exclusivity harms all consumers. Consumer surplus effects depend on the taste distribution: under logit demand exclusivity is always harmful, whereas under uniform tastes it can raise consumer surplus at intermediate levels of competition. With demand asymmetries, the larger firm wins exclusivity and consumer harm is smaller. Banning only large-firm exclusivity (partial ban) can reduce welfare and consumer surplus compared to laissez-faire or a complete ban.

We study consumer-optimal learning with continuously distributed valuations when a monopolist adjusts its product line in response. We identify smooth environments in which every optimum requires pooling buyers at the same expected willingness to pay, inducing discrete lower-quality products alongside a continuous range of higher-quality options. Optimal learning can also exclude buyers despite gains from trade. Under our main assumptions, buyers in an upper interval of valuations learn their values exactly, and we characterize when full information is optimal. Finally, relaxing the stronger assumptions on the valuation distribution can lead to complex learning patterns, with infinitely many separate regions of partial learning even under regular priors and quadratic costs. Remarkably, different priors can require very different patterns of learning while leading the seller to offer exactly the same products and prices.

When does information manipulation protect regimes from coordinated attacks? This paper revisits Edmond (2013) and develops a general framework encompassing political unrest, bank runs, and currency crises.  We establish a condition for unique equilibrium outcomes in monotone strategies: stronger fundamentals must outweigh the largest possible shifts in collective attacks. Otherwise, nonmonotone equilibria can emerge. Our main result shows that manipulation can be ineffective in the sense that it can reduce attacks without improving survival because it benefits regimes that would survive anyway. We fully characterize when manipulation is effective, ineffective, or absent, regardless of whether manipulators pool or separate. Our findings highlight the limitations of accounting discretion as a tool to prevent bank runs and promote financial stability.

Coordination facilitation and efficient decision-making are two essential components of successful leadership. In this paper, we take an informational approach and investigate how followers' information impacts coordination and efficient leadership in a model featuring a leader and a team of followers. We show that efficiency is achieved as the unique rationalizable outcome of the game when followers possess sufficiently imprecise information. In contrast, if followers have accurate information, the leader may fail to coordinate them toward the desired outcome or even take an inefficient action herself. We discuss the implications of the results for the role of leaders in the context of financial fragility and crises.