I am an Assistant Professor of Economics at NYU Shanghai. Previously, I was an Assistant Professor at the University of Edinburgh, and before that, at the University of Groningen. From 2014 to 2016, I was a postdoctoral researcher at the University of Pennsylvania. I received my PhD from the University of Wisconsin, Madison.
I graduated from the mathematical economics program at the Corvinus University of Budapest. I grew up in Gyula, Hungary.
My research is in Mechanism Design and Market Design. I like to think and talk about externalities, moment conditions in economic design, information aggregation, information design in exchanges, uniform price market clearing, and game theoretic solution concepts such as rationalizability under various assumptions on beliefs.
Contact: mo2639 at nyu dot edu
Contact: mo2639 at nyu dot edu
Publications:
Publications:
[1] A Network Solution to Robust Implementation: the Case of Identical but Unknown Distributions, with Antonio Penta
[1] A Network Solution to Robust Implementation: the Case of Identical but Unknown Distributions, with Antonio Penta
REStud 2023, Keywords: Robust Full Implementation, Interdependent Values, Rationalizability, Identical but Unknown Distributions, Network Design, Uniqueness, Strategic Externalities, Spectral Radius, pdf
REStud 2023, Keywords: Robust Full Implementation, Interdependent Values, Rationalizability, Identical but Unknown Distributions, Network Design, Uniqueness, Strategic Externalities, Spectral Radius, pdf
[2] Efficient Full Implementation via Transfers: Uniqueness and Sensitivity in Symmetric Environments, with Antonio Penta
[2] Efficient Full Implementation via Transfers: Uniqueness and Sensitivity in Symmetric Environments, with Antonio Penta
[3] Full Implementation and Belief Restrictions, with Antonio Penta
[3] Full Implementation and Belief Restrictions, with Antonio Penta
AER 2017, Keywords: Unique Δ-Rationalizability, Full Implementation, Belief Restrictions, Moment Conditions, Robust Mechanism Design, pdf
AER 2017, Keywords: Unique Δ-Rationalizability, Full Implementation, Belief Restrictions, Moment Conditions, Robust Mechanism Design, pdf
[4] Monotonicity and Robustness of Majority Rule
[4] Monotonicity and Robustness of Majority Rule
EL 2010, Keywords: Majority rule, Monotonicity, Well-working, Continuum Number of Voters, Diverse Domain, pdf
EL 2010, Keywords: Majority rule, Monotonicity, Well-working, Continuum Number of Voters, Diverse Domain, pdf
Working Papers:
[1] Incentive Compatibility and Belief Restrictions, with Antonio Penta
[1] Incentive Compatibility and Belief Restrictions, with Antonio Penta
We study implementation in environments with possibly interdependent values where the designer's robustness criterion is given via belief sets B. We provide a first-order approach to the design of the transfers that are robustly incentive compatible wrt. beliefs in B. Our smooth settings are fairly general with respect to agents' valuations and the designer's goal. Our general characterizations provide insights on possibilities for environments which may violate the classic properties such as single-crossing or monotonicity. One key takeaway from our approach is that comovement of agents' payoff-types can be meaningfully used to implement allocation rules even when the robustness requirement does not allow the use of enough information about beliefs to extract the full surplus. slides
We study implementation in environments with possibly interdependent values where the designer's robustness criterion is given via belief sets B. We provide a first-order approach to the design of the transfers that are robustly incentive compatible wrt. beliefs in B. Our smooth settings are fairly general with respect to agents' valuations and the designer's goal. Our general characterizations provide insights on possibilities for environments which may violate the classic properties such as single-crossing or monotonicity. One key takeaway from our approach is that comovement of agents' payoff-types can be meaningfully used to implement allocation rules even when the robustness requirement does not allow the use of enough information about beliefs to extract the full surplus. slides
[2] Beliefs and Transfers in Multidimensional Mechanism Design, with Antonio Penta and Gabriel Ziegler
[2] Beliefs and Transfers in Multidimensional Mechanism Design, with Antonio Penta and Gabriel Ziegler
This paper highlights possibilities of implementation with multidimensional types in environments with transfers. We study multiple agents with interdependent values, multidimensional private information - possibly be correlated across agents, smooth valuation functions and allocation rules. Multidimensional ex-post incentive compatibility is impossible unless the environment satisfies a notion of symmetry expressed as the "integral condition" in Wilson (1993) and, more generally in Jehiel et al. (2006). The latter show that this condition is non-generic in multiple precise senses. However, as we point out in this paper, interim incentive compatibility is substantially less demanding. The interim possibilities are important for applications in auctions, bundling, as well as, taxation. We demonstrate how to construct the transfers that ensure the desired outcomes by way of using minimal information available about agents' beliefs.
This paper highlights possibilities of implementation with multidimensional types in environments with transfers. We study multiple agents with interdependent values, multidimensional private information - possibly be correlated across agents, smooth valuation functions and allocation rules. Multidimensional ex-post incentive compatibility is impossible unless the environment satisfies a notion of symmetry expressed as the "integral condition" in Wilson (1993) and, more generally in Jehiel et al. (2006). The latter show that this condition is non-generic in multiple precise senses. However, as we point out in this paper, interim incentive compatibility is substantially less demanding. The interim possibilities are important for applications in auctions, bundling, as well as, taxation. We demonstrate how to construct the transfers that ensure the desired outcomes by way of using minimal information available about agents' beliefs.
[3] Robust Implementation via Transfers: the Case of General Smooth Valuations, with Antonio Penta
[3] Robust Implementation via Transfers: the Case of General Smooth Valuations, with Antonio Penta
We study robust full implementability with a focus on successively stronger knowledge assumptions on beliefs. Agents' private information is single-dimensional. We study the design of transfers that uniquely implement the desired allocation but elicit only agents' payoff relevant information. One knowledge assumption we focus on is when agents have common belief that others' types are identically distributed without the distribution being commonly known among the agents nor known to the designer (common belief in identicality). Along with this assumption, we also present the parallel results for the two extreme assumptions: the belief-free case and the case with commonly known priors. Several results from Ollár and Penta (2017) and Ollár and Penta (2023) already provide insights under linearity assumptions. Here we show that the qualitative insights extend to a larger class of environments with general valuations and allocations. Additionally, we study the limits of these extensions: in each belief-setting, we derive the alignment of preferences as they relate to the strategic externalities of the allocation problem that is needed for implementation. We are motivated by allocation problems which typically would not satisfy the previous linearity assumptions, for example, due to congestion effects or peer-dependent usage value.
We study robust full implementability with a focus on successively stronger knowledge assumptions on beliefs. Agents' private information is single-dimensional. We study the design of transfers that uniquely implement the desired allocation but elicit only agents' payoff relevant information. One knowledge assumption we focus on is when agents have common belief that others' types are identically distributed without the distribution being commonly known among the agents nor known to the designer (common belief in identicality). Along with this assumption, we also present the parallel results for the two extreme assumptions: the belief-free case and the case with commonly known priors. Several results from Ollár and Penta (2017) and Ollár and Penta (2023) already provide insights under linearity assumptions. Here we show that the qualitative insights extend to a larger class of environments with general valuations and allocations. Additionally, we study the limits of these extensions: in each belief-setting, we derive the alignment of preferences as they relate to the strategic externalities of the allocation problem that is needed for implementation. We are motivated by allocation problems which typically would not satisfy the previous linearity assumptions, for example, due to congestion effects or peer-dependent usage value.
[4] Information Design and Stability in Exchanges
[4] Information Design and Stability in Exchanges
This paper shows a limitation of information design in exchanges with uniform price market clearing. In these exchanges, improving traders' surplus through a better choice of the information structure conflicts with the stability of the exchange: traders' surplus is higher if information sources are less correlated, however, the less correlated the information sources are the closer the exchange is to the boundary of the set of stable exchanges. This paper also shows that under better information structures, traders' orders are closer to market orders.
This paper shows a limitation of information design in exchanges with uniform price market clearing. In these exchanges, improving traders' surplus through a better choice of the information structure conflicts with the stability of the exchange: traders' surplus is higher if information sources are less correlated, however, the less correlated the information sources are the closer the exchange is to the boundary of the set of stable exchanges. This paper also shows that under better information structures, traders' orders are closer to market orders.
Keywords: Information Design in Exchanges, Uniform Price Market Clearing, Price-Dependent Orders, Price Informativeness, Stability of Trade
[5] Measurement Errors and Information Aggregation in Exchanges
[5] Measurement Errors and Information Aggregation in Exchanges
In financial and commodity exchanges, traders gain information from shared information sources, such as commonly accessed forecasts and standardized reports, thus traders' information is likely to exhibit common bias in measurement errors. This paper shows in a linear normal model (following Kyle (89)) that when forecast errors are correlated, then this presence of non-iid. errors may prevent full aggregation of information, moreover, segmented trading can improve informativeness of the price. Because of learning about errors, the price is informative even on markets with independent values. The price is uninformative if the error correlations are the same as value correlations. This paper illuminates previous monotonicity results for iid. errors and common values, and more generally shows that the relationship between error and value correlations is key to monotonicity of information aggregation in market size.
In financial and commodity exchanges, traders gain information from shared information sources, such as commonly accessed forecasts and standardized reports, thus traders' information is likely to exhibit common bias in measurement errors. This paper shows in a linear normal model (following Kyle (89)) that when forecast errors are correlated, then this presence of non-iid. errors may prevent full aggregation of information, moreover, segmented trading can improve informativeness of the price. Because of learning about errors, the price is informative even on markets with independent values. The price is uninformative if the error correlations are the same as value correlations. This paper illuminates previous monotonicity results for iid. errors and common values, and more generally shows that the relationship between error and value correlations is key to monotonicity of information aggregation in market size.
Keywords: Information Aggregation, Correlated Forecast Errors, Price-Dependent Orders, Price Informativeness, Market Size
[6] Consumption Externalities and Competing Sellers: Efficiency Ranking of Market Structures
[6] Consumption Externalities and Competing Sellers: Efficiency Ranking of Market Structures
The efficiency ranking of market structures is qualitatively affected by the nature of buyer side peer interactions. To show this, I formulate a model for a two-sided market with competing sellers and a network of buyers whose willingness to purchase varies according to their peers' purchases. Examples of such markets include competing small businesses, on-line music and video streaming services and publishers in advertisement exchanges. I allow for the joint presence of positive and negative peer influences and define overall positive and overall negative peer influence based on a vector aggregate of the exerted marginal influence on others' choices. I show that typical market structures (here competition in prices, competition in fees and price setting by a centralized platform) do not internalize the efficiency distortions caused by the externalities. In particular, with overall positive peer influence competition in membership fees dominates competition in prices while with overall negative peer influence this conclusion reverses.
The efficiency ranking of market structures is qualitatively affected by the nature of buyer side peer interactions. To show this, I formulate a model for a two-sided market with competing sellers and a network of buyers whose willingness to purchase varies according to their peers' purchases. Examples of such markets include competing small businesses, on-line music and video streaming services and publishers in advertisement exchanges. I allow for the joint presence of positive and negative peer influences and define overall positive and overall negative peer influence based on a vector aggregate of the exerted marginal influence on others' choices. I show that typical market structures (here competition in prices, competition in fees and price setting by a centralized platform) do not internalize the efficiency distortions caused by the externalities. In particular, with overall positive peer influence competition in membership fees dominates competition in prices while with overall negative peer influence this conclusion reverses.
Keywords: Efficiency Ranking, Network Externalities, Price Competition, Social Interactions
[7] Rationalizable Implementation and Delta-Restrictions, with Antonio Penta
[7] Rationalizable Implementation and Delta-Restrictions, with Antonio Penta
We introduce a framework to study full implementation under general restrictions on agents' conjectures, which we call Delta-Implementation. These general restrictions are set-valued Delta-restrictions which, for instance, include Belief Restrictions as well as Behavioral Restrictions. We provide a characterization of the properties of general mechanisms that achieve Full Delta-Implementation and relate this to known notions of implementation.
We introduce a framework to study full implementation under general restrictions on agents' conjectures, which we call Delta-Implementation. These general restrictions are set-valued Delta-restrictions which, for instance, include Belief Restrictions as well as Behavioral Restrictions. We provide a characterization of the properties of general mechanisms that achieve Full Delta-Implementation and relate this to known notions of implementation.
Old Working Papers:
[++] Full Implementation under Identical but Unknown Distributions, with Antonio Penta, long version, pdf
[++] Full Implementation under Identical but Unknown Distributions, with Antonio Penta, long version, pdf