Aaron Yoon - Faculty & Research - Harvard Business School
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Aaron Yoon

Doctoral Student

Aaron S. Yoon is a doctoral candidate in Accounting and his research interests are in the capital markets (institutional investors, portfolio management, security analysts, and sustainability), with a focus on the forces and mechanisms that shape accounting information.

Prior to Harvard, Yoon worked as an equity trader and quant research analyst at Credit Suisse and also controlled air traffic in the 8th US Army. He holds an MA in Economics and BA in Economics and Mathematical Methods in the Social Sciences from Northwestern University.

Journal Articles
  1. Corporate Sustainability: First Evidence on Materiality

    Mozaffar Khan, George Serafeim and Aaron Yoon

    Using newly available materiality classifications of sustainability topics, we develop a novel dataset by hand-mapping sustainability investments classified as material for each industry into firm-specific sustainability ratings. This allows us to present new evidence on the value implications of sustainability investments. Using both calendar-time portfolio stock return regressions and firm-level panel regressions we find that firms with good ratings on material sustainability issues significantly outperform firms with poor ratings on these issues. In contrast, firms with good ratings on immaterial sustainability issues do not significantly outperform firms with poor ratings on the same issues. These results are confirmed when we analyze future changes in accounting performance. The results have implications for asset managers who have committed to the integration of sustainability factors in their capital allocation decisions.

    Keywords: sustainability; Investments; corporate social responsibility; accounting; corporate reporting; regulation; Corporate Social Responsibility and Impact; Integrated Corporate Reporting; Investment; Corporate Governance;


    Khan, Mozaffar, George Serafeim, and Aaron Yoon. "Corporate Sustainability: First Evidence on Materiality." Accounting Review 91, no. 6 (November 2016).  View Details
Working Papers
  1. Private and Public Disclosures in Countries with Weak Institutional Environments: Evidence from Shanghai-Hong Kong Connect

    Aaron Yoon

    I study firms’ use of disclosure to build investor confidence when they operate in a market where the institutions that support the supply of credible information are weak. Using the announcement of a regulation that allowed foreigners to invest in select Shanghai firms, I examine how the eligible firms responded vis-à-vis the ineligible firms. I find that the eligible firms increased private disclosures ahead of the new regime’s implementation, motivated by their desire to attract capital. Those firms experienced an increase in foreign investment after the regulation’s implementation and exhibited higher foreign holdings and lower volatility during a subsequent market crash. Taken together, the results suggest that disclosure is a mechanism which firms use to build trust and credibility towards sophisticated investors.

    Keywords: Corporate Disclosure; Reputation; Institutional Investing; Trust;

  2. Shareholder Activism on Sustainability Issues

    Jody Grewal, George Serafeim and Aaron Yoon

    Shareholder activism on sustainability issues has become increasingly prevalent over the years, with the number of proposals filed doubling from 1999 to 2013. We use recent innovations in accounting standard setting to classify 2,665 shareholder proposals that address environmental, social, and governance (ESG) issues as financially material or immaterial, and we analyze how proposals on material versus immaterial issues affect firms’ subsequent ESG performance and market valuation. We find that 58% of the shareholder proposals in our sample are filed on immaterial issues. We document that filing shareholder proposals is effective at improving the performance of the company on the focal ESG issue, even though such proposals nearly never received majority support. Improvements occur across both material and immaterial issues. Proposals on immaterial issues are associated with subsequent declines in firm valuation while proposals on material issues are associated with subsequent increases in firm value. We show that companies increase performance on immaterial issues because of agency problems, low awareness of the materiality of ESG issues, and attempts to divert attention from poor performance on material issues.

    Keywords: sustainability; activism; Activist Investors; Activist shareholder; corporate social responsibility; corporate accountability; environment; Corporate performance; corporate governance; Corporate Accountability; Corporate Social Responsibility and Impact; Performance; Environmental Sustainability; Corporate Governance; Business and Shareholder Relations; Investment Activism;


    Grewal, Jody, George Serafeim, and Aaron Yoon. "Shareholder Activism on Sustainability Issues." Harvard Business School Working Paper, No. 17-003, July 2016.  View Details