MARZENA ROSTEK

 RESEARCH INTERESTS: MICROECONOMIC THEORY, MARKET DESIGN, FINANCE


Theory and Design of Divisible Good Markets

  •  “Price Inference in Small Markets” (with M. Weretka), Econometrica 80, 2 (2012), 687-711. PDF
        The literature on information aggregation suggests that larger markets unambiguously improve price inference. These results have been developed for markets where the values of all traders for the exchanged good are determined by a fundamental (common) shock. Heterogeneity in (income, endowment, liquidity, or preference) shocks underlying trader values changes the predictions of the classical model: Smaller markets may offer opportunities to learn from prices that are not available in large markets.
     
  •  “Demand Reduction and Inefficiency in Multi-Unit Auctions” (with with L. Ausubel, P. Cramton, M. Pycia, and M. Weretka), Conditionally Accepted, The Review of Economic Studies, available by e-mail.
        Auctions often involve the sale of multiple units of goods or assets; Treasury, emission permits, electricity, repo and spectrum are examples. We examine (in)efficiency and revenue for the commonly used multi-unit auction formats. We explain the new incentives through multi-unit features, not present in auctions with unit demands, such as multi-unit but constant marginal utility and diminishing marginal utility.
     
  •  “Welfare Trade-offs and Private Information” (with M. Weretka), Revise and Resubmit, The Journal of Economic Theory, available by e-mail.
        Does encouraging trader participation enhance market competitiveness? When trader preferences are interdependent, for natural information structures, larger markets may be less efficient, less liquid and be characterized by lower per capita welfare.
     
  •  “Privacy-Preserving Market Design” (with M. Ollar and J. H. Yoon).

Decentralized Markets

  •  “Decentralized Exchange” (with S. Malamud), available by e-mail.
        Assets and goods are increasingly traded away from public exchanges. This paper develops an equilibrium model of decentralized trading that accommodates any networked markets with coexisting exchanges represented by hypergraphs. We identify economic effects that do not have centralized-market counterparts.

Optimization and Games in Spans: Applications to Financial Innovation, Information Disclosure, and Bundling Many economic problems involve sellers choosing collections of “bundles” in order to maximize the bundles’ market value. Instances of optimization over bundles include issuance of asset-backed securities by real asset holders, choosing a portfolio of risky assets to offer by central banks and Treasury Departments, and selection of product variety by multiproduct sellers with a bundle interpreted as a product with multiple continuous characteristics or attributes. To study these economic problems, the following introduce and analyze a class of single-agent problems and games in which strategies are spans.

  •  “Competition in Financial Innovation” (with A. Carvajal and M. Weretka), Econometrica 80, 5 (2012), 1895-1936. PDF
        A piece on endogenous (in)completeness of market structures. When does competition in financial innovation among asset owners provide sufficient incentives to create and complete markets?  In economies with convex marginal utility, any financial structure with an incomplete set of securities brings higher market value of the assets than a complete financial structure, even if innovation is costless. Thus, if market efficiency is to be improved through asset innovation, incentives other than maximization of asset value are necessary. This paper introduces games over spans, which can be useful in modeling competition beyond the financial application.
     
  •  “On Information Releases and Asset Prices” (with A. Carvajal and G. Sublet), available by e-mail.
     
  •  “Bundling without Price Discrimination” (with A. Carvajal and M. Weretka), available by e-mail.
        In the literature, the central motivation for bundling is that it allows sellers to price discriminate buyers. The ability to price discriminate requires that the seller can monitor individual purchases and resale markets be limited or absent—in essence, some form of limits to arbitrage. In some markets, including financial, there are significant arbitrage opportunities and thus non-linear pricing is not available. This paper demonstrates a new mechanism that gives rise to bundling profitability, even in markets with arbitrary arbitrage possibilities. Thus, as a tool to increase profits, bundling need not rely on price discrimination.

Qualitative Decision Making

  •  Quantile Maximization in Decision Theory,” The Review of Economic Studies 77 (2010), 339-371. PDF
        This paper introduces a model of preferences in which an individual compares uncertain alternatives through a quantile of the induced utility distributions. The choice rule of Quantile Maximization nests maxmin and maxmax but also captures less extreme scenario-based or order-statistics analysis. Quantile Maximization, unlike Expected Utility or any cardinal model, can provide a decision theory for environments in which the alternatives involve categorical variables (e.g., quality ratings, professions, grades); as well as a more general way of expressing a preference for robustness to own utility’s assessments. It can also be used in policy implementation for populations with heterogeneous preferences in which a decision maker’s only knowledge about preferences is that people prefer more to less.

Thin Markets

  •  “Dynamic Thin Markets” (with M. Weretka), available by e-mail.
        Many markets, including financial, are thin in that trade is dominated by a group of large agents who have price impact. The assumption of price-taking behavior underlies many central results in asset pricing, in particular the no-arbitrage principle and full diversification of risk. This paper develops an equilibrium foundation for the illiquidity that arises from price impact. Dynamic bilateral price impact changes both the efficiency and arbitrage properties of equilibrium in ways not anticipated either by static models with bilateral price impact or dynamic models with one-sided market power.

     
  •  “Thin Markets” (with M. Weretka), The New Palgrave Dictionary of Economics Online (2008), Steven N. Durlauf and Lawrence E. Blume, Eds. Palgrave Macmillan.

Misc

  •  Price Discrimination and Resale” (with A. Basuchoudhary, C. Metcalf, K. Pommerenke, D. H. Reiley, C. Rojas, and J. Stodder), The Journal of Economic Education (2008), 39 (3), 229-244.

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