資本市場中，會計師事務所之專業性與獨立性備受投資大眾之信任，且向來以提供高品質審計服務著稱，本研究旨在檢測會計師事務所發生資料外洩事件後，分析師對已查核財務報表所作盈餘預測之誤差與離散程度是否有所上升，故蒐集2005年至2018年美國上市公司資料作為樣本，共計17,080筆觀察值。實證結果顯示，當會計師事務所爆發資料外洩事件後，由於聲譽的受損使得分析師對會計師事務所查核公司的盈餘預測誤差與離散程度均顯著增加，惟審計品質並未有所改變，可見事務所品質管制制度仍相當重要。於額外分析中進一步發現，資料外洩事件的類型並未提供強烈證據支持該事件與分析師預測特性之關聯，然而，Deloitte在2017年發生之資料外洩事件後，由於規模龐大且涉及國家或政府的機敏資訊，加劇分析師盈餘預測之誤差與離散程度。整體而言，本研究強調會計師事務所爆發資料外洩事件後，分析師對該所查核公司盈餘預測之影響，實證結果應能提供會計師事務所、美國上市公司財務報表使用者及政府部門，建立品質管理制度、進行投資決策與政策制定方面的參考。

This study investigates the impact of data breaches at audit firms on financial analysts’ earnings forecasts. Based on a sample of data breaches in US from 2005 to 2018, I examine whether audit firm’s data breaches affect analysts’ information environment. I find that clients audited by audit firms with data breaches exhibit a deterioration in analyst forecast properties, as proxied by forecast errors and forecast dispersion. One possible reason is that auditor reputation is impaired after such breaches, leading to a significant increase in both analysts' forecast errors and dispersion for their clients. However, I find no evidence that the adverse effects of data breaches on analysts’ forecasts vary with breach type and audit quality, implying that audit firms’ quality management systems may remain effective in maintaining audit quality. Furthermore, I find that Deloitte suffered significant reputational damage after its 2017 data breaches, it exerts a more pronounced adverse impact on forecast accuracy and dispersion. Overall, my study highlights the implications of data breaches on auditor reputation in capital markets and provides decision-useful information for regulators, audit firms, and external financial statement users.

Ashraf, M. 2022. The role of peer events in corporate governance: Evidence from data breaches. The Accounting Review 97 (2): 1–24.
Acquisti, A., Friedman, A., and Telang, R. 2006. Is there a cost to privacy breaches? An event study. ICIS 2006 proceedings, 94. https://aisel.aisnet.org/icis2006/94
Alhusaini, B., Lamoreaux, P. T., Newton N. J. 2025. IPOs and Auditor Reputation: Evidence from Audit Firm Data Breaches. The Accounting Review 100 (5):1–25.
Appel, I., Gormley, T., Keim, D., 2016. Passive investors, not passive owners. Journal of Financial Economics 121 (1): 111-141.
Ang, J. S., and S. J. Ciccone. 2001. International differences in analyst forecast properties. Working paper, University of New Hampshire.
Bamber, L. S., J. Jiang, and I. Y. Wang. 2010. What’s my style? The influence of top managers on voluntary corporate financial disclosure. The Accounting Review, 85 (4): 1131–1162.
Barron, O. E., Byard, D., Kile, C., and Riedl, E. J. 2002. High-technology intangibles and analysts’ forecasts. Journal of Accounting Research 40(2): 289–312.
Bradley, Daniel, Gokkaya, Sinan, Liu, Xi. 2017. Before an analyst becomes an analyst: does industry experience matter? The Journal of Finance 72: 751-792.
Bradshaw, M., and R. Sloan. 2002. GAAP versus the street: An empirical assessment of two alternative definitions of earnings. Journal of Accounting Research 40: 41−66.
Brown, L. 1997. Analyst forecasting errors: Additional evidence. Financial Analyst Journal 53 (6): 81–88.
Behn, B., Choi, J.H., Kang, T. 2008. Audit quality and properties of analyst earnings forecasts. The Accounting Review 83 (2): 327–359.
Cahan, S. F., P. K. Chaney, D. C. Jeter, and W. Zhang. 2013. Damaged auditor reputation and analysts’ forecast revision frequency. Auditing: A Journal of Practice and Theory 32 (1): 33–60.
Campbell, K., Gordon, L., Loeb, M., and Zhou, L. 2003. The economic cost of publicly announced information security breaches: Empirical evidence from the stock market. Journal of Computer Security 11(3): 431–448.
Cavusoglu, H., Mishra, B., and Raghunathan, S. 2004. The effect of internet security breach announcements on market value: Capital market reactions for breached firms and internet security developers. International Journal of Electronic Commerce 9(1): 70–104.
Clement, M. B. 1999. Analyst forecast accuracy: do ability, resources, and portfolio complexity matter? Journal of Accounting and Economics 27 (3): 285–303.
Clement, M., and S. Tse. 2005. Financial analyst characteristics and herding behavior in forecasting. Journal of Finance 60: 307−341.
Chang, H. S., Donohoe, M., and Sougiannis, T. 2016. Do analysts understand the economic and reporting complexities of derivatives? Journal of Accounting and Economics, 61 (2–3): 584–604.
Chen, M., Zhu, Z., Han, P., Chen, B. and Liu, J. 2022. Economic policy uncertainty and analyst behaviours: Evidence from the United Kingdom. International Review of Financial Analysis 79, Article 101906.
Chen, C. Y., Goh, B. W., Lee, J., Li, N. 2026. The Effect of Cybersecurity Breaches on Analysts’ Earnings Forecasts. European Accounting Review 35 (1): 263-289.
Chen, X., Chen, J., Chen, R., Hasan, M., Zhang. X. 2025. Fortifying the Nonbreached: Auditors’ Role in Cybersecurity Risk Management. Auditing: A journal of practice & theory: 1–27.
Chung, K. H., and H. Zhang. 2011. Corporate Governance and Institutional Ownership. Journal of Financial and Quantitative Analysis, 46 (1): 247-273.
Chuang, W. I. and Lee, B. S. 2011. The informational role of institutional investors and financial analysts in the market. The Journal of Finance 14 (3): 465–493.
Cuculiza, C., Alok K., Wei X., and Chendi Z. 2021, Climate Change, Analyst Forecasts, and Market Behavior, Available at SSRN 3781157.
Das, S., C. B. Levine, and K. Sivaramakrishnan. 1998. Earnings predictability an earnings forecasts. The Accounting Review 73 (2): 277-294.
Das, S., Mukhopadhyay, A., and Anand, M. 2012. Stock market response to information security breach: A study using firm and attack characteristics. Journal of Information Privacy and Security 8(4): 27-55.
DeAngelo, L. E. 1981. Auditor size and audit quality. Journal of Accounting and Economics, 3(3): 183-199.
Dichev, I.D., and V.W. Tang. 2009. Earnings volatility and earnings predictability. Journal of Accounting and Economics 47: 160-181.
Diether, K., C. Malloy, and A. Scherbina. 2002. Differences of opinion and the cross section of stock returns. Journal of Finance 57 (5): 2113−2141.
Dopuch, N., and D. Simunic. 1980. The Nature of Competition in the Auditing Profession: A Descriptive and Normative View. Regulation and the Accounting Profession 34(2): 283 89.
Duffie, D. and Younger, J., 2019. Cyber Runs. Hutchins Center Unpublished Working Paper 51. Brookings Institution.
Duru, Augustine, Reeb, David M., 2002. International diversification and analysts’ forecast accuracy and bias. The Accounting Review 77 (2): 415–433.
Fang, V. W. 2009. The role of management forecast precision in predicting management forecast error. Working Paper, University of Minnesota. https://ssrn.com/abstract = 1446346.
Federal Bureau of Investigation (FBI). 2023. Federal Bureau of Investigation Internet Crime Report 2022. Internet Crime Complaint Center.
Feng, M. and S. McVay. 2010. Analysts’ Incentives to Overweight Management Guidance When Revising Their Short-Term Earnings Forecasts. The Accounting Review 85 (5): 1617–1646.
Florackis, C., C. Louca, R. Michaely, and M. Weber. 2023. Cybersecurity risk. The Review of Financial Studies 36 (1): 351–407.
Francis, J. R., and Wang, D. 2005. Impact of the SEC's public fee disclosure requirement on subsequent period fees and implications for market efficiency. Auditing: A Journal of Practice & Theory, 24(1): 145-160.
Francis, J.R., S.S. Neuman, and N.J. Newton. 2019. Does tax planning affect analysts’ forecast accuracy? Contemporary Accounting Research 36 (4): 2663-2694.
Garg, A., Curtis, J., and Halper, H. 2003. Quantifying the financial impact of IT security breaches. Information Management & Computer Security 11(2): 74-83.
https://doi.org/10.1108/09685220310468646
Garel, A., Martin-Flores, J. M., Petit-Romec, A. and Scott, A. 2021. Institutional investor distraction and earnings management. Journal of Corporate Finance 66, 101801.
Givoly, D., and J. Lakonishok. 1984. Properties of analysts' forecasts of earnings: A review and analysis of the research. Journal of Accounting Literature 3: 117−152.
Gillan, S., and L. Starks. 2003. Corporate governance, corporate ownership, and the role of institutional investors: A global perspective. Journal of Applied Finance 13: 4-22.
Gleason, C., and Lee, C. 2003. Analyst forecast revisions and market price discovery. The Accounting Review 78(1): 193–225.
Gordon, L. A., Loeb, M. P., and Sohail, T. 2010. Market value of voluntary disclosures concerning information security. MIS Quarterly 34(3): 567–594.
https://doi.org/10.2307/25750692
Goel, S., and Shawky, H. A. 2009. Estimating the market impact of security breach announcements on firm values. Information & Management 46(7): 404–410.
Graham, J. R., 1999, Herding among investment newsletters: Theory and evidence, Journal of Finance 54 (1): 237-268.
Gu, Feng, Wang, Weimin, 2005. Intangible assets, information complexity, and analysts’ earnings forecasts. Journal of Business Research 32: 1673–1702.
Gu, Z., Z. Li, Y. G. Yang. 2013. Monitors or Predators: The Influence of Institutional Investors on Sell-Side Analysts. The Accounting Review 88 (1): 137–169.
Gwebu, K. L., Wang, J., and Wang, L. 2018. The role of corporate reputation and crisis response strategies in data breach management. Journal of Management Information Systems 35 (2): 683–714.
Hazarika, S., Karpoff, J. M., Nahata, R. 2012. Internal corporate governance, CEO turnover, and earnings management. Journal of Financial Economics 104 (1): 44-69.
Haw, I., K. Jung, and W. Ruland. 1994. The accuracy of financial analysts' forecasts after mergers. Journal of Accounting, Auditing and Finance 9: 465–483.
Harford, J., F. Jiang, R. Wang, F. Xie. 2019. Analyst Career Concerns, Effort Allocation, and Firms’ Information Environment. The Review of Financial Studies 32 (6): 2179–2224.
He, C. Z., T. Frost, and R. E. Pinsker. 2020. The impact of reported cybersecurity breaches on firm innovation. Journal of Information Systems 34 (2): 187-209.
Healy, P. M., A. P. Hutton, K. G. Palep. 1999. Stock performance and intermediation changes surrounding sustained increases in disclosure. Contemporary Accounting Research 16 (3): 485–520.
Higgs, J. L., R. E. Pinsker, T. J. Smith, and G. R. Young. 2016. The relationship between board-level technology committees and reported security breaches. Journal of Information Systems 30 (3): 79-98.
Holden, C. W. and P. S. Stuerke. 2008. The frequency of financial analysts’ forecast revisions: theory and evidence about determinants of demand for predisclosure information. Journal of Business Finance & Accounting 35 (7–8): 860–888.
Hope, Ole-Kristian, T. Kang. 2005. The association between macroeconomic uncertainty and analysts’ forecast accuracy. Journal of International Accounting Research 4 (1): 23–38.
Hopkins, N. 2017. Deloitte hit by cyber-attack revealing clients’ secret emails. The Guardian. https://www.theguardian.com/business/2017/sep/25/deloitte-hit-by-cyber-attack-revealing-clients-secret-emails
Hong, H., J. D. Kubik. 2003. Analyzing the analysts: career concerns and biased earnings forecasts. The Journal of Finance 58 (1): 313–351.
Hilary, G., L. Menzly. 2006. Does past success lead analysts to become overconfident? Management Science 52 (4): 489–500.
Hope, Ole-Kristian. 2003. Disclosure practices, enforcement of accounting standards, and analysts’ forecast accuracy: an international study. Journal of Accounting Research 41 (2): 235–272.
Hossain, M. S., H. Belina, M. M. Hasan, and M. M. Kim. 2025. The Effects of Auditor-level Cybersecurity Breaches on Auditor-Client Relationships. European Accounting Review 34 (6): 1–28.
Hui, K. W., and S. R. Matsunaga. 2015. Are CEOs and CFOs rewarded for disclosure quality? The Accounting Review 90 (3): 1013–1047.
Hwang, L., C. Jan, and S. Basu. 1996, Loss firms and analysts’ earnings forecast errors. Journal of Financial Statement Analysis 1: 18‐30.
Johnson, T. 2004. Forecast dispersion and the cross section of expected returns. Journal of Finance 59: 1957−1978.
Jurgens, J. and D. C. Paolo. 2025 Global Cybersecurity Outlook 2025. World Economic Forum. https://reports.weforum.org/docs/WEF_Global_Cybersecurity_Outlook_2025.pdf
Kamiya, S., J. K. Kang, J. Kim, A. Milidonis, and R. M. Stulz. 2021. Risk management, firm reputation, and the impact of successful cyberattacks on target firms. Journal of Financial Economics 139 (3): 719–749.
Kim, I., Lee, S., Ryou, J. 2024. Does climate risk influence analyst forecast accuracy? Journal of Financial Stability 75, Article 101345.
Keskek, S., Tse, S. Y. 2018. Does forecast bias affect financial analysts’ market influence? Journal of Accounting, Auditing and Finance 33 (4): 601–623.
Kross, W., B. Ro, and D. Schroeder. 1990. Earnings expectations: The analysts’ information advantage. The Accounting Review 65 (2): 461–476.
Krueger, P., Sautner, Z., and Starks, L. T. 2020. The importance of climate risks for institutional investors. The Review of Financial Studies 33 (3): 1067–1111.
Lang, M.H., and Lundholm, R. J. 1996. Corporate disclosure policy and analyst behavior. The Accounting Review 71 (4): 467–492.
Leuz, C., Wysocki, P. D. 2016. The Economics of Disclosure and Financial Reporting Regulation: Evidence and Suggestions for Future Research. Journal of Accounting Research 54 (2): 525–622.
Li, C. K., J. H. Luo, and N. S. Soderstrom. 2020. Air pollution and analyst information production. Journal of Corporate Finance 60, 101536.
Litt B., T. Paul, W. W. Marcia. 2023. Cybersecurity Breach at a Big 4 Accounting Firm: Effects on Auditor Reputation. Journal of Information Systems 37 (2): 77–100.
Li H., Z. Sun, and F. Huang. 2024. The Impact of Audit Office Cybersecurity Experience on Nonbreach Client's Audit Fees and Cybersecurity Risks. Journal of Information Systems 38 (1): 177–206.
Lin K.C. and X. Dong. 2025. Climate policy uncertainty and analyst forecast quality for greenhouse gas-intensive firms. Advances in Accounting 68, 100817.
Lin, M. C. 2018. The impact of aggregate uncertainty on herding in analysts’ stock recommendations. International Review of Financial Analysis 57: 90–105.
Lys, T., and L.G. Soo. 1995. Analysts' forecast precision as a response to competition. Journal of Accounting, Auditing and Finance 10 (4): 751-765.
McCahery, J.A., Sautner, Z., Starks, L.T., 2016. Behind the scenes: the corporate governance preferences of institutional investors. The Journal of Finance 71: 2905–2932.
Mattei, M. M., Platikanova, P. 2017. Do product market threats affect analyst forecast precision? Review of Accounting Studies 22 (4): 1628–1665.
Parkash M., D.S. Dhaliwal, and W.S. Salatka. 1995. How certain firm-specific characteristics affect the accuracy and dispersion of analysts' forecasts: a latent variables approach. Journal of Business Research 34 (3):161–169.
Petersen, M. A. 2009. Estimating standard errors in finance panel data sets: Comparing approaches. Review of Financial Studies 22 (1): 435–480.
Richardson, V. J., Smith, R. E., and Watson, M. W. 2019. Much ado about nothing: The (lack of) economic impact of data privacy breaches. Journal of Information Systems 33 (3), 227-265. https://doi.org/10.2308/isys-52379
Rosati, P., Gogolin, F., Lynn, T. 2020. Cyber Security Incidents and Audit Quality, European Accounting Review 31 (3): 701–728
Rosati, P., Cummins, M., Deeney, P., Gogolin, F., van der Werff, L., and Lynn, T. 2017. The effect of data breach announcements beyond the stock price: Empirical evidence on market activity. International Review of Financial Analysis 49: 146–154.
Schatz, D., and Bashroush, R. 2016. The impact of repeated data breach events on organizations’ market value. Information and Computer Security 24 (1): 73–92.
Sheneman, A.G. 2026. Cybersecurity risk and bank loan contracting. The Accounting Review 101 (1): 475-502
Song, M., Kim, D., and Won, C. 2009. Earnings uncertainty and analyst forecast herding. Asia‐Pacific Journal of Financial Studies 38 (4): 545-574.
Tan, H., Wang, S., Welker, M. 2011. Analyst following and forecast accuracy after mandated IFRS adoptions. Journal of Accounting Research 49 (5): 1307–1357.
Trueman, B. 1994. Analyst forecasts and herding behavior. The review of financial studies 7 (1): 97-124.
Tanimura, J. K., and Wehrly, E. W. 2015. The market value and reputational effects from lost confidential information. International Journal of Financial Management 5 (4): 18-35.
Welch, I. 2000. Herding among security analysts. Journal of Financial Economics 58: 369−386.
Weber, D.P. 2009. Do analysts and investors fully appreciate the implications of book-tax differences for future earnings? Contemporary Accounting Research 26 (4): 1175-1206.
Xu, H., Guo, S., Haislip, J. Z., and Pinsker, R. E. 2019. Earnings management in firms with data security breaches. Journal of Information Systems 33 (3): 267-284.
Yang, H. I. 2012. Capital market consequences of managers’ voluntary disclosure styles. Journal of Accounting and Economics, 53 (1): 167–184.
Yayla, A. A., and Hu, Q. 2011. The impact of information security events on the stock value of firms: The effect of contingency factors. Journal of Information Technology 26 (1): 60-77.
Zhang, X.F. 2006. Information uncertainty and analyst forecast behavior. Contemporary Accounting Research 23: 565−590.
Zhang, L., and K. Kanagaretnam. 2025. Climate Disasters and Analysts’ Earnings Forecasts:Evidence from the United States. European Accounting Review 34 (3): 1277-1304.