This study examines the relationship between GDP fluctuations and private investment using a macro-panel approach across five selected South Asian countries — Bangladesh, India, Nepal, Pakistan, and Sri Lanka — for the period 1980–2010. The study applies modern non-stationary panel techniques including cross-sectional dependency tests and the Group Mean Fully Modified OLS (GM-FMOLS) estimator to assess long-run relationships. Results shed light on the investment-deterrent or investment-neutral effects of GDP volatility in the South Asian context, contributing to the literature on uncertainty, irreversibility, and the private investment response to macroeconomic instability in developing economies.