Rory Mullen

Working Papers

Works in Progress

Firm Technology Usage

with Jesus Gorrin

Technology is central to economics, but current technology datasets fail to meet the needs of economists because they lack scale, scope, span, or specificity. We apply natural language processing and positive and unlabeled machine learning to patent descriptions and business descriptions from U.S. public firms over three decades to produce a firm-level technology dataset that offers an unrivaled combination of these characteristics. We identify the core technologies of patent non-owning firms, estimate the value to these firms of innovations to the core technologies they use, and show how stock market participants inefficiently process technological information on these firms, leading to profitable trading strategies.

Investment Completion Risk and Stock Returns

with Ajay Venkataraman and Arie E. Gozluklu

We examine the impact of investment completion risk on the stock market performance of clean energy firms, isolating the completion risk channel in a theoretical model and testing the channel using project-level data from the U.S. nuclear and wind industries. We find that completion risk substantially raises the cost of capital for clean energy investments. For the nuclear industry, a 1 percentage point rise in completion risk corresponds to a 36 basis point rise in stock returns, after controlling for investment cost. In a case study, we interpret heightened regulatory scrutiny following the 1979 Three Mile Island nuclear accident as a shock to completion risk and find that completion risk strengthens as a return predictor after the accident. In Fama-MacBeth regressions, we find that nuclear completion risk is priced, particularly for firms with complex technologies. Evidence from the renewable wind industry supports our main findings from the nuclear industry.

Latest Updates

May 2025

Huge thanks to Pierre De Leo for his insightful discussion of my co-authored paper "Foreign Exchange Interventions and Intermediary Constraints" at SFS Cavalcade NA this year. Grateful to be included in such a strong program!

May 2025

The International Conference on Empirical Economics hosted by Penn State accepted my co-authored paper "Foreign Exchange Interventions and Intermediary Constraints" for a virtual presentation on Zoom, 2 August!

April 2025

The Econometric Society World Congress accepted my co-authored paper "Who Carries?", looking forward to presenting in Seoul!

April 2025

Excited that our paper "Who Carries?" was accepted to the World Finance Conference in Malta—looking forward to connecting with researchers in international finance.

March 2025

Great to meet the University of Exeter Macro Group and present my paper, "On Aggregate Fluctuations." Thank you for the invitation and the insightful comments!

March 2025

New paper! "Who Carries?" now on SSRN. We bridge a finance literature on carry trade with an international macro literature on portfolio home bias in this work.

October 2024

European Winter Meeting of the Econometric Society accepted my co-authored paper "Who Carries?." Just finished a major revision, so looking forward to presenting in Palma!

October 2024

New paper! "Foreign Exchange Interventions and Intermediary Constraints now on SSRN." Sterilized interventions work, but crowd out private intermediation.

April 2024

CEBRA Annual Meeting accepted my co-authored paper "Foreign Exchange Interventions and Intermediary Constraints," very excited to be back in Frankfurt!