We examine the effect of CEO childhood socioeconomic status (SES) on firm risk. Using hand‐collected data on US CEOs' private high‐school attendance as proxy for high‐SES, we find that firms led by high‐SES CEOs exhibit 5.35% lower firm risk. This effect diminishes with CEO tenure, analyst coverage, and institutional ownership, consistent with the market expectations hypothesis. High‐SES CEOs do not differ in corporate risk‐taking, incentives, ability, performance, or crisis management. Our findings support the SES theory, which suggests that socioeconomic background acts as a signal that shapes investor expectations, rather than reflecting differences in CEO behaviour or competence.