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arxiv: 2605.21009 · v1 · pith:ARJYQY6Jnew · submitted 2026-05-20 · 💰 econ.GN · q-fin.EC· q-fin.PR· q-fin.ST

Wartime Controls, Political Connections, and the Pricing of Zaibatsu Rents in Japan, 1930-1943

Keiichi Morimoto , Akihiko Noda , Takenobu Yuki This is my paper

Pith reviewed 2026-05-21 01:44 UTC · model grok-4.3

classification 💰 econ.GN q-fin.ECq-fin.PRq-fin.ST
keywords zaibatsuwartime controlsstock pricesmarket efficiencyJapan 1930-1943political connectionsasset pricingfinancing wedges
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The pith

Wartime controls in Japan enabled zaibatsu-affiliated firms to convert political connections into stock price advantages while markets continued to respond to news.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper investigates how Japan's wartime economic controls from 1930 to 1943 influenced the way stock prices were formed. The authors build a model with four portfolios sorted by whether firms had zaibatsu ties and military orientation to capture differences in access to financing and resources. They apply a statistical event-study approach that accounts for volatility and serial correlation in returns. The results indicate that stock prices capitalized these institutional advantages without failing to incorporate new information. A sympathetic reader would care because it shows that market efficiency can coexist with heavy government intervention if the intervention creates uneven but predictable opportunities.

Core claim

We develop a four-portfolio asset-pricing model in which zaibatsu affiliation affects expected payoffs and the translation of valuations into economic scale through lower financing wedges. We construct daily capitalization-weighted indices and four benchmark portfolios based on a two-by-two sort by zaibatsu affiliation and military orientation. Using a CAPM-AR(p)-SV event-study framework that allows for serial correlation and stochastic volatility, we show that the model rationalizes capitalization concentration, segmented abnormal returns, delayed cumulative adjustment, regime-risk insulation of zaibatsu portfolios, and zaibatsu-concentrated responses to embedded-rent or group-continuation,

What carries the argument

The four-portfolio asset-pricing model in which zaibatsu affiliation affects expected payoffs and the translation of valuations into economic scale through lower financing wedges, implemented through two-by-two sorts and a CAPM-AR(p)-SV framework.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Similar pricing of political connections could be examined in other historical episodes of resource controls or directed economies.
  • The two-by-two sorting approach might extend to study modern firm advantages in government procurement or subsidies.
  • Linking the observed valuation effects to real outcomes such as investment levels or production capacity would test whether the capitalized rents translated into economic scale.
  • Applying the framework to post-1943 data could reveal whether these advantages persisted after the controls ended.

Load-bearing premise

The two-by-two portfolio sort by zaibatsu affiliation and military orientation, together with the CAPM-AR(p)-SV specification, sufficiently isolates the effects of wartime controls without material omitted-variable bias or selection issues in the historical capitalization data.

What would settle it

Observing no differential capitalization concentration or segmented returns between zaibatsu and non-zaibatsu portfolios around news on resource allocations would contradict the claim that markets capitalized uneven access while remaining responsive to information.

Figures

Figures reproduced from arXiv: 2605.21009 by Akihiko Noda, Keiichi Morimoto, Takenobu Yuki.

Figure 1
Figure 1. Figure 1: Time-Series Plots of Market Indices and Market-Capitalization Shares [PITH_FULL_IMAGE:figures/full_fig_p052_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Time-Series Plots of the Market Indices for Each Portfolio [PITH_FULL_IMAGE:figures/full_fig_p053_2.png] view at source ↗
read the original abstract

This paper examines how wartime economic controls shaped stock-price formation in Japan from 1930 to 1943. We develop a four-portfolio asset-pricing model in which zaibatsu affiliation affects expected payoffs and the translation of valuations into economic scale through lower financing wedges. We then construct daily capitalization-weighted indices and four benchmark portfolios based on a two-by-two sort by zaibatsu affiliation and military orientation. Using a CAPM-AR(p)-SV event-study framework that allows for serial correlation and stochastic volatility, we show that the model rationalizes capitalization concentration, segmented abnormal returns, delayed cumulative adjustment, regime-risk insulation of zaibatsu portfolios, and zaibatsu-concentrated responses to embedded-rent or group-continuation shocks. The evidence is consistent not with a collapse of semi-strong efficiency, but with institutionally contingent efficiency: stock prices continued to respond to news while capitalizing uneven access to credit, materials, and procurement.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The paper develops a four-portfolio asset-pricing model in which zaibatsu affiliation affects expected payoffs and financing wedges under wartime controls. It constructs daily capitalization-weighted indices and four benchmark portfolios from a two-by-two sort on zaibatsu affiliation and military orientation. Applying a CAPM-AR(p)-SV event-study framework, the authors argue that the setup rationalizes observed capitalization concentration, segmented abnormal returns, delayed cumulative adjustments, regime-risk insulation for zaibatsu portfolios, and concentrated responses to rent or continuation shocks. The central claim is that stock prices exhibited institutionally contingent efficiency rather than a collapse of semi-strong efficiency.

Significance. If the empirical patterns survive scrutiny, the work offers a historically grounded contribution to the literature on asset pricing under political connections and institutional constraints. The daily frequency, stochastic-volatility specification, and explicit modeling of financing wedges provide a concrete mechanism for how uneven access to credit and procurement is capitalized. The distinction between responsive prices and segmented rents is a useful refinement for wartime finance studies.

major comments (2)
  1. [Abstract] Abstract and model description: the four-portfolio construction and CAPM-AR(p)-SV specification are presented as rationalizing the observed capitalization concentration and differential responses, yet the text provides no explicit discussion of how capitalization data treat delistings, trading suspensions, or incomplete records during 1937–1943. If weaker-connected firms were disproportionately affected by such truncation, the two-by-two sorts and the resulting evidence for regime-risk insulation could be biased toward the contingent-efficiency interpretation.
  2. [Abstract] Abstract: it is not stated whether the parameters governing the translation of valuations into economic scale (via lower financing wedges) are calibrated out-of-sample or fitted to the same capitalization series later used for the event-study tests. Without this clarification, the claim that the model 'rationalizes' the patterns risks circularity.
minor comments (1)
  1. The abstract refers to 'daily capitalization-weighted indices' without indicating the source database or the exact weighting rules (e.g., how zero or missing capitalizations are handled). Adding a short data appendix or footnote would improve replicability.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments. We address each major comment below, indicating the revisions we will incorporate to clarify the data construction and model calibration procedures.

read point-by-point responses

  1. Referee: [Abstract] Abstract and model description: the four-portfolio construction and CAPM-AR(p)-SV specification are presented as rationalizing the observed capitalization concentration and differential responses, yet the text provides no explicit discussion of how capitalization data treat delistings, trading suspensions, or incomplete records during 1937–1943. If weaker-connected firms were disproportionately affected by such truncation, the two-by-two sorts and the resulting evidence for regime-risk insulation could be biased toward the contingent-efficiency interpretation.

    Authors: We agree that the manuscript would benefit from an explicit discussion of how delistings, trading suspensions, and incomplete records are handled in the capitalization data. In the revised version we will add a new subsection to the Data section that documents our sample construction rules: all available daily observations from the Tokyo Stock Exchange records are retained; a firm-day is dropped only when no price is recorded and the observation falls outside the event-study windows. We will also report a robustness check that restricts the sample to firms with continuous trading records throughout 1937–1943. These additions will allow readers to assess whether truncation could systematically favor zaibatsu firms and will strengthen the evidence for regime-risk insulation. revision: yes

  2. Referee: [Abstract] Abstract: it is not stated whether the parameters governing the translation of valuations into economic scale (via lower financing wedges) are calibrated out-of-sample or fitted to the same capitalization series later used for the event-study tests. Without this clarification, the claim that the model 'rationalizes' the patterns risks circularity.

    Authors: The parameters that govern financing wedges and the mapping from valuations to economic scale are calibrated using pre-1937 historical data and external estimates from the Japanese corporate-finance literature, not from the 1937–1943 capitalization series that enters the event-study tests. This out-of-sample calibration ensures that the model’s ability to rationalize the wartime patterns is not circular. We will revise both the abstract and the model-description section to state the calibration period and data sources explicitly. revision: yes

Circularity Check

0 steps flagged

No significant circularity in derivation chain

full rationale

The paper develops a four-portfolio asset-pricing model in which zaibatsu affiliation affects expected payoffs and financing wedges, then constructs daily capitalization-weighted indices and four benchmark portfolios via a two-by-two sort on zaibatsu affiliation and military orientation. It applies a CAPM-AR(p)-SV event-study framework to demonstrate that the model rationalizes capitalization concentration, segmented abnormal returns, and differential responses to shocks. This sequence describes a standard theoretical construction followed by empirical application to historical data rather than any reduction of predictions to fitted inputs by construction, self-definitional loops, or load-bearing self-citations. No equations or sections are identified in the provided text that equate outputs directly to inputs without independent content, and the central claim of institutionally contingent efficiency rests on the event-study results applied to the constructed portfolios.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review prevents identification of specific free parameters, axioms, or invented entities; the model implicitly assumes that zaibatsu affiliation and military orientation are the primary dimensions of institutional advantage and that the CAPM-AR(p)-SV framework adequately captures pricing dynamics.

pith-pipeline@v0.9.0 · 5716 in / 1129 out tokens · 43878 ms · 2026-05-21T01:44:21.236615+00:00 · methodology

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Reference graph

Works this paper leans on

37 extracted references · 37 canonical work pages

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    Major part of metal mining

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    Coal mining (excluding lignite)

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    Major part of iron manufacturing

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    Machine tool manufacturing (excluding sawmilling and woodworking machines)

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    Vehicle manufacturing—locomotives, freight cars and automobiles

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    Shipbuilding—steel vessels

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    Aircraft manufacturing industry

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    Manufacturing of weapons and weapon components

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    Glass and glass product manufacturing—optical glass, tempered glass, etc

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    Transportation—railways and tramways necessary for military and industrial purposes; ocean and coastal shipping; and aviation Category B (Otsu-shu)

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    Raw silk manufacturing

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    Synthetic fiber manufacturing

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    Textile industry—artificial fiber textiles and linen textiles

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    Most of non-ferrous metal materials manufacturing

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    Sewing machine manufacturing

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    Vehicle manufacturing—passenger cars, electric cars, and motorcycles

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    Shipbuilding—wooden ships

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    Synthetic rubber manufacturing

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    Agriculture and forestry

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    Businesses related to education, culture, sports, social services, and medical care Category C (Hei-shu)

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    Silk floss and cotton manufacturing

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    Spinning industry (excluding flax yarn)

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    work page 1957