Investment risk is a core concept within finance and economics that quantifies the uncertainty associated with the potential outcomes of an investment, particularly the probability of incurring a financial loss or failing to achieve expected returns. This academic concept investigates the various sources of variability in investment performance, exploring methodologies for its measurement, assessment, and management. Its key characteristics include its multi-faceted nature, encompassing market, credit, liquidity, and operational risks among others, and its fundamental relationship with expected return, often posited as a trade-off. The significance of studying investment risk lies in its critical role in informing rational investment decisions, optimizing portfolio construction, pricing assets, and contributing to the stability and regulation of financial markets.