The Geography of Worker-Firm Sorting: Drivers of Rising Colocation
Nils Torben Hollandt, Steffen Müller
IWH Discussion Papers,
No. 22,
2025
Abstract
Spatial segregation of low- and high-wage workers is a persistent economic issue with broad social implications. Using social security data and an AKM wage decomposition, this paper examines spatial wage inequality in West Germany. Spatial inequality in log wages rose sharply between 1998 and 2008, mainly due to increased variance in worker pay premiums across regions (48%) and stronger positive spatial assortative matching of workers and establishments (40%), i.e. colocation. Changes in establishment wage premia are mostly unrelated to rising colocation whereas labor mobility even reduced it. Instead, growth in worker pay premiums among stayers was concentrated in regions where high-wage workers and high-wage establishments were overrepresented already in the 1990s and, thus, magnified pre-existing colocation leading to ‘colocation without relocation’. Germany’s rising trade surplus, especially with Eastern Europe, boosted stayers’ worker pay premiums in those ex-ante high-wage regions and fully explains rising colocation.
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The Contribution of Employer Changes to Aggregate Wage Mobility
Nils Torben Hollandt, Steffen Müller
Oxford Economic Papers,
No. 2,
2025
Abstract
Wage mobility reduces the persistence of wage inequality. We develop a framework to quantify the contribution of employer-to-employer movers to aggregate wage mobility. Using three decades of German social security data, we find that inequality increased while aggregate wage mobility decreased. Employer-to-employer movers exhibit higher wage mobility, mainly due to changes in employer wage premia at job change. The massive structural changes following German unification temporarily led to a high number of movers, which in turn boosted aggregate wage mobility. Wage mobility is much lower at the bottom of the wage distribution, and the decline in aggregate wage mobility since the 1980s is concentrated there. The overall decline can be mostly attributed to a reduction in wage mobility per mover, which is due to a compositional shift toward lower-wage movers.
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Media Response January 2026 IWH: Ein seltsamer Rekord in: Frankfurter Allgemeine Sonntagszeitung, 11.01.2026 Steffen Müller: Zahl der Insolvenzen auf 20-Jahres-Hoch in: Welt am…
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The Contribution of Employer Changes to Aggregate Wage Mobility
Nils Torben Hollandt, Steffen Müller
Abstract
Wage mobility reduces the persistence of wage inequality. We develop a framework to quantify the contribution of employer-to-employer movers to aggregate wage mobility. Using three decades of German social security data, we find that inequality increased while aggregate wage mobility decreased. Employer-to-employer movers exhibit higher wage mobility, mainly due to changes in employer wage premia at job change. The massive structural changes following German unification temporarily led to a high number of movers, which in turn boosted aggregate wage mobility. Wage mobility is much lower at the bottom of the wage distribution, and the decline in aggregate wage mobility since the 1980s is concentrated there. The overall decline can be mostly attributed to a reduction in wage mobility per mover, which is due to a compositional shift toward lower-wage movers.
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Trade Shocks, Labour Markets and Migration in the First Globalisation
Richard Bräuer, Felix Kersting
Economic Journal,
No. 657,
2024
Abstract
This paper studies the economic and political effects of a large trade shock in agriculture—the grain invasion from the Americas—in Prussia during the first globalisation (1870–913). We show that this shock led to a decline in the employment rate and overall income. However, we do not observe declining per capita income and political polarisation, which we explain by a strong migration response. Our results suggest that the negative and persistent effects of trade shocks we see today are not a universal feature of globalisation, but depend on labour mobility. For our analysis, we digitise data from Prussian industrial and agricultural censuses on the county level and combine them with national trade data at the product level. We exploit the cross-regional variation in cultivated crops within Prussia and instrument with Italian and United States trade data to isolate exogenous variation.
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Three Essays on Cross-Firm Interactions
William McShane
PhD Thesis, Otto-von-Guericke-Universität Magdeburg,
2023
Abstract
Competition in the U.S. appears to have declined. One contributing factor may have been heterogeneity in the availability of credit during the financial crisis. I examine the impact of product market peer credit constraints on long-run competitive outcomes and behavior among non-financial firms. I use measures of lender exposure to the financial crisis to create a plausibly exogenous instrument for product market credit availability. I find that credit constraints of product market peers positively predict growth in sales, market share, profitability, and markups. This is consistent with the notion that firms gained at the expense of their credit constrained peers. The relationship is robust to accounting for other sources of inter-firm spillovers, namely credit access of technology network and supply chain peers. Further, I find evidence of strategic investment, i.e. the idea that firms increase investment in response to peer credit constraints to commit to deter entry mobility. This behavior may explain why temporary heterogeneity in the availability of credit appears to have resulted in a persistent redistribution of output across firms.
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