IT Sector Stock Performance Under Artificial Intelligence Disruption a Comparative Event Study of TCS, Infosys and HCL Technologies on the NSE

Abstract Purpose: This paper examines whether discrete artificial intelligence announcements produced abnormal equity returns in India's three largest information technology services firms, and whether market-implied resilience corresponds to resilience visible in audited financial statements.Design and methodology: The study applies a single-index market model event study to Tata Consultancy Services, Infosys and HCL Technologies over 988 aligned trading sessions from 1 July 2022 to 30 June 2026. Six events are verified against primary announcements. Normal returns are estimated over a ninety-session window ending six sessions before each event, with abnormal returns tested using Patell standardisation and supported by four robustness checks.Findings: The launch of ChatGPT produced no statistically measurable abnormal return in the sample. Significant three-session cumulative average abnormal returns of -3.03 per cent, -3.21 per cent and -4.16 per cent were recorded around the DeepSeek-R1 repricing session, the Anthropic COBOL modernisation publication and the Accenture guidance reduction respectively. Capability shocks partly reversed; the demand shock did not.Originality and value: The article contributes a primary-source-verified event calendar for artificial intelligence disruption in Indian IT equities, demonstrates the benchmark absorption problem in sectoral event studies, and documents a tension between market-implied resilience and audited margin evidence.