cost-overrun

An unexpected cost increase that causes project expenditures to exceed the originally budgeted or estimated amount.

A cost overrun occurs when the actual cost of completing a project exceeds its initial budget. This is a common operational risk in capital-intensive industries such as mining, infrastructure, utilities, and manufacturing, where projects span several years and are subject to inflation, supply chain delays, and engineering challenges. For investors, cost overruns are a major red flag. They directly erode the projected return on investment (ROI) of a project, drain corporate cash reserves, and often force companies to raise dilutive equity capital or take on expensive debt to fund the shortfall. When a company announces a cost overrun, it typically triggers an immediate downward re-rating of the stock. Investors analyze cost overruns by comparing the final or current projected capital expenditure (capex) against the initial feasibility study or budget. Persistent overruns across multiple projects suggest poor management execution, weak internal controls, or unrealistic initial forecasting, which can permanently damage a company's valuation.

Company A estimates that building a new lithium processing plant will cost $1.0 billion. Due to labor shortages and equipment inflation, the final cost rises to $1.31 billion. The cost overrun is calculated as ($1.31 billion - $1.0 billion) / $1.0 billion = 0.31, or a 31% cost overrun.