Stewardship, Fiduciary Duty, and the Cost Structure of Asset Management
Hiroyasu Omura
SSRN Electronic Journal, Apr. 2026
This article reexamines the theory of stewardship from the perspective of institutional alignment among fiduciary duty, investment mandates, investment strategies, and the cost structures of asset managers. Recent debates on stewardship have largely focused on the growing influence of large institutional investors, particularly passive asset managers, and have framed stewardship as a normative question of whether such influence should be exercised more actively or constrained. However, these debates do not sufficiently explain the institutional and economic conditions that shape asset managers' behavior. Drawing on fiduciary law theory and the economics of asset management, this article argues that voting should be understood as a core obligation derived from the duty of loyalty, while engagement should be understood as a discretionary activity derived from the duty of care, the content of which should vary depending on investment mandates and cost-recovery structures. The article demonstrates that the uniform stewardship model embedded in stewardship codes creates institutional misalignment across investment 2 strategies and proposes a role-differentiated stewardship framework based on investment mandates as a foundation for institutional design.

The Mandate-fit Theory of Stewardship : Passive Investing and the Institutional Structure of Asset Management
Hiroyasu Omura
SSRN Electronic Journal, Apr. 2026
<div> The rapid expansion of passive investing has reshaped debates on corporate governance and stewardship. Existing literature focuses on the growing influence of large index fund managers and advances competing normative arguments regarding whether their role should be strengthened or constrained. However, these debates largely overlook the institutional structure of asset management, including investment mandates and cost structures.&nbsp;</div><div> <br></div><div> This article develops the mandate-fit theory, which explains stewardship as the alignment between fiduciary duties, investment mandates, investment strategies, and cost structures. Voting is derived from the duty of loyalty, while engagement depends on the duty of care and the contractual mandate.&nbsp;</div><div> <br></div><div> The analysis shows that active and passive strategies generate different forms of stewardship. Active managers undertake firm-level engagement, whereas passive managers primarily conduct systematic stewardship through voting. These differences arise from the economic structure of asset management.&nbsp;</div><div> <br></div><div> The article argues that stewardship should not be understood as a uniform obligation. Instead, it should be viewed as an institutional outcome shaped by mandates, strategies, and cost structures, and calls for greater transparency in investment mandates.</div>

Corporate Governance in Capital Markets
Hiroyasu Omura
Springer Nature Switzerland, 25 Aug. 2025

Stewardship Responsibilities in the Perspectives of Fiduciary Law and Asset Managers’ Cost Analysis
Hiroyasu Omura
Nov. 2024

Stewardship Responsibilities in the Perspectives of Fiduciary Law and Asset Managers' Cost Analysis
Hiroyasu Omura
SSRN Electronic Journal, 2024

コーポレートガバナンス改革後のスチュワードシップ活動とエー ジェンシー問題　　　　　　　　　　　　　　　
Sep. 2020

日本におけるコーポレートガバナンス改革の意義　　　　　　　　　　　　　　　
Jun. 2020

What Does Japanese Corporate Governance Reform Mean?
Hiroyasu Omura
SSRN Electronic Journal, 2020

Stewardship Activities and Agency Problems after Japanese Corporate Governance Reform
Hiroyasu Omura
SSRN Electronic Journal, 2020

制度的側面から見たコーポレートガバナンス論
Dec. 2008

Corporate Governance in Capital Markets: Navigating Governance Systems of Publicly Traded Firms (CSR, Sustainability, Ethics & Governance)
Contributor, Chapter of Japan
Springer Cham, Aug. 2025, [Reviewed]
9783031947513

コーポレートガバナンス改革後のスチュワードシップ活動とエー ジェンシー問題　　　　　　　　　　　　　　　
13 Sep. 2020, [Invited]

May 2021 - Present
European Corporate Governance Institute　　　　　　　　　　　　　　　

Nov. 2019 - Present
Society for the Economic Studies of Securities　　　　　　　　　　　　　　　

Aug. 1993 - Present
The Securities Analysts Association of Japan