Center of Applied Economic Studies of the Atlantic

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Organizational Unit

Publications

Stock market effects of corporate malpractices and misconduct: evidence from the short-seller Hindenburg

Publication . Albuquerque, Bruno; Martins, António Miguel Valente; Moutinho, Nuno

This study used event study methodology to examine the impact Hindenburg Research shortseller reports on targeted firms. The results show negative abnormal returns in firms when those reports reveal bad news about malpractices and misconduct. Our results show a higher negative stock market reaction to the Hindenburg reports when target firms are small, have higher leverage, higher Tobin’s Q, and corporate malpractice involves financial fraud. Our findings evidence that adverse information disclosed in the Hindenburg report led to a “torpedo effect”, resulted in sharp, immediate, and persistent share price drops.

2025Journal article

Open access

The effect of the evergrande bankruptcy on Chinese real estate listed firms

Publication . Martins, António Miguel Valente; Moutinho, Nuno

The objective of the study is to examine the intra-industry effects of Evergrande’s bankruptcy on the Chinese real estate listed firms. Based on an event study, we evidence a negative and statistically significant stock price reaction to Evergrande’s bankruptcy announcement. These results are consistent with the contagion effect. We also find the highest negative impact on real estate firms with greater leverage and a higher similarity in cash flows with the bankrupt firm. Finally, the magnitude of the stock market reaction to Evergrande’s bankruptcy is reinforced or mitigated by firm-specific determinants such as size and liquidity.

2024Journal article

Open access

Stock-term market impact of major cyber-attacks: evidence for the ten most exposed insurance firms to cyber risk

Publication . Martins, António Miguel Valente; Moutinho, Nuno

The main focus of this paper is to study empirically the impact of major cyberattacks in the market value of the ten most exposed insurers to cyber risk. Using an event study for 53 global cyberattacks, we observe a negative and statistically significant stock price reaction for insurers around the cyberattack disclosure dates. The increase in the assessed probability of an increase in future payments tends to prevail over the increase in demand and/or premiums caused by the disclosure of global major cyberattacks. The results of our analysis also show a higher negative stock market reaction for small insurers and when involves financial information loss.

2025Journal article

Open access

Airline stock market reaction to CrowdStrike IT outage: an event study analysis

Publication . Costa, João; Cró, Susana; Moutinho, Nuno; Martins, António Miguel

This study investigates the short-term market effect of CrowdStrike IT outage in the airline industry. Using an event study methodology, we evidence that airline stocks respond significantly negatively to the technology disruption within two days before and after the event day. IT disruptions, by creating friction in daily operations, such as broken schedules, delayed or cancelled flights, negative externalities, and customer dissatisfaction, lead to loss of value for airlines. The results also show that the most affected airlines are those from main CrowdStrike customers countries (mainly non-Asian countries) and an irrelevance of the business model. Finally, the extent of the stock market’s response to the CrowdStrike IT outage is influenced by other airline characteristics such as profitability, size, leverage, and cyber risk rating.

2025Journal article

Open access

Stock market effects of CrowdStrike IT outage on largest listed hotel companies

Publication . Albuquerque, Bruno; Cró, Susana; Moutinho, Nuno; Martins, António Miguel

This study analyses the short-term market effect of CrowdStrike IT outage in the 100 largest worldwide listed hotel companies. Using an event study methodology, the paper analyses how hotel companies are penalized by the market to the biggest IT disruption in history. Our results evidence a statistically significant negative reaction around the event date. This result is explained by the adverse impact caused by IT failures in the hotel’s business operations (reservation, payment, technical systems) and supply chain processes, which result in financial losses. We also observe a highest negative stock market reaction for hotel companies located in Western countries and for hotels with a low cyber risk rating. Finally, this study identifies hotel-specific characteristics that drive value during an IT outage. The research evidence that larger and more profitable hotel companies, with lower leverage and higher cyber risk ratings are more resilient to the adverse effects of IT outages.

2025Journal article

Open access