Stock-based compensation (SBC) reduces the value of shareholder equity, ceteris paribus, and is a significant and growing expense for many firms. Despite its valuation implications and its growing importance, anecdotal evidence suggests that market participants ignore SBC in valuation. We first find that firms with higher SBC exhibit both higher valuation ratios and lower returns, suggesting overvaluation. This pattern is stronger for firms with larger analyst coverage, implying that the sell-side optimism is an important driver of the overvaluation. We then examine how financial analysts treat SBC in their valuation models. We find that analysts exclude SBC in their street earnings forecasts and provide more optimistically biased target prices for firms with higher SBC. A hand-collected sample of analyst reports indicates that analysts who ignore SBC in valuation derive optimistically biased price targets, whereas analysts who treat SBC as an expense are unbiased on average. Together, our evidence indicates that market participants’ failure to account for stock-based compensation as an expense leads to the overvaluation of equity.