Date/Time
Date(s) - 17/04/2026
11:00 am - 12:30 pm

Mahmood Haddara, PhD student at the University of Toronto, will present to our graduate students and faculty in KTH 334!

Mahmood Haddara is a macroeconomist whose research studies topics such as aggregate productivity, innovation, and trade. He is currently a PhD candidate at the University of Toronto and will begin a Weatherall Postdoctoral Fellowship at Queen’s University in July 2026.

He will present, “Customer Accumulation, Firm Size, and Aggregate Productivity“.

Abstract

Firms differ in how well they can produce as well as how many customers they can sell to. In this paper, I study the possibility of mismatch between these two objects: productive firms with few customers and unproductive firms with many. I argue that this is an important channel for understanding firm size dispersion and a key determinant of aggregate productivity. To do so, I develop a dynamic macroeconomic model where firms endogenously differ in both productivity and customer access. Customer accumulation in the model is gradual and uncertain, naturally allowing for productivity-customer mismatch. I show that the firm’s static optimality conditions distinguish customer access from productivity, allowing me to separately identify the two objects in firm-level data. Applying this method to administrative data covering the universe of Canadian firms, I uncover a surprising degree of mismatch. This leads to a strong policy implication: A tax on high-revenue firms — clearly detrimental in standard models — can increase aggregate productivity and welfare. This is because the tax shifts production away from unproductive large firms, reducing misallocation by enough that the net effect is positive.

Learn more about Mahmood’s work and connect with him through his professional website.