Merger enforcement in two-sided markets

This paper studies mergers in two-sided markets by estimating a structural supply and demand model and performing counterfactual experiments. The analysis is performed on data for a merger wave in U.S. radio that occurred between 1996 and 2006. The paper makes two main contributions. First, I identify the conflicting incentives of merged firms to exercise market power on both sides of the market (listeners and advertisers in the case of radio). Second, I disaggregate the effects of mergers on consumers into changes in product variety and changes in supplied ad quantity. I find that firms have moderate market power over listeners in all markets, extensive market power over advertisers in small markets and no market power over advertisers in large markets. Counterfactuals reveal that extra product variety created by post-merger repositioning increased listeners' welfare by 1.3% and decreased advertisers' welfare by about $160m per-year. However, subsequent changes in supplied ad quantity decreased listener welfare by 0.4$140m (for a total impact of -$300m).

Estimation of cost synergies from mergers without cost data: Application to U.S. radio

This paper develops a new way to estimate cost synergies from mergers without using actual data on cost. The estimator uses a structural model in which companies play a dynamic game with endogenous mergers and product repositioning decisions. Such a formulation has several benefits over the widespread static merger analysis. In particular, it corrects for sample selection of more profitable mergers and captures follow-up mergers and post-merger product repositioning. The framework is applied to estimate cost efficiencies after the deregulation of U.S. radio in 1996. The procedure uses the data on radio station characteristics and numerous acquisitions, without explicit need for cost data. It turns out that between 1996 and 2006 additional ownership concentration generated $2.5b per-year cost savings, which is about 10% of total industry revenue.

What Makes them Click: Empirical Analysis of Consumer Demand for Search Advertising

We study users' response to sponsored-search advertising using data from Microsoft's Live AdCenter distributed in the "Beyond Search" initiative. We estimate a structural model of utility maximizing users, which quantifies "user experience" based on their "revealed preferences," and predicts user responses to counterfactual ad placements. In the model, each user chooses clicks sequentially to maximize his expected utility under incomplete information about the relevance of ads. We estimate the substitutability of ads in users' utility function, the fixed effects of different ads and positions, user uncertainty about ads' relevance, and user heterogeneity. We find substantial substitutability of ads, which generates large negative externalities: 40% more clicks would occur in a hypothetical world in which each ad faces no competition. As for counterfactual ad placements, our simulations indicate that CTR-optimal matching increases CTR by 10.1% while user-optimal matching increases user welfare by 13.3%. Moreover, targeting ad placement to specific users could raise user welfare by 59%. Here, we find a significant suboptimality (up to 16% of total welfare) in case the search engine tries to implement a sophisticated matching policy using a misspecified model that does not account for externalities. Finally, user welfare could be raised by 14% if they had full information about the relevance of ads to them.

Closed-form expressions for correlated density matrices: application to dispersive interactions and example of (He)2

Empirically correlated density matrices of N-electron systems are investigated. Exact closed-form expressions are derived for the one- and two-electron reduced density matrices from a general pairwise correlated wave function. Approximate expressions are proposed which reflect dispersive interactions between closed-shell centro-symmetric subsystems. Said expressions clearly illustrate the consequences of second-order correlation effects on the reduced density matrices. Application is made to a simple example: the (He)2 system. Reduced density matrices are explicitly calculated, correct to second order in correlation, and compared with approximations of independent electrons and independent electron pairs. The models proposed allow for variational calculations of interaction energies and equilibrium distance as well as a clear interpretation of dispersive effects on electron distributions. Both exchange and second order correlation effects are shown to play a critical role on the quality of the results.Comment: 22 page