Testing Market Resilience and Adaptability: An Empirical Analysis of Weak-Form Efficiency in Indian Benchmark Indices (2018–2023)

Abstract The Indian equity market has witnessed a paradigm shift driven by rapid digitalization, regulatory reforms, and broadened investor participation. This study rigorously evaluates the weak-form efficiency of the Indian stock market by analyzing the BSE Sensex and NSE Nifty 50 indices over a volatile six-year period (2018–2023). Utilizing logarithmic return analysis, volatility estimation, and the Runs Test for randomness, the research posits that while the Indian market largely adheres to weak-form efficiency, it exhibits "adaptive" characteristics where efficiency is temporarily compromised during exogenous shocks like the COVID-19 pandemic. The findings indicate that price movements are predominantly random, yet the market demonstrated a significant behavioral deviation in 2020, followed by a robust correction facilitated by enhanced information dissemination. This paper offers critical insights for policymakers and portfolio managers regarding the interplay between market volatility and information efficiency.