The paper examines an understudied aspect in the literature on employee mobility and innovation—the impact of employee stock options on talent allocation. My research reconciles between two schools of thought regarding noncompete agreement by highlighting the role of Silicon Valley’s business norm of granting stock options to virtually all employees. This custom emerged during Silicon Valley’s inception as an alternative model to the more centralized and hierarchical organizational culture of East Coast corporate America, which held that companies should reserve equity grants solely to senior management. My work suggests that Silicon Valley start-ups can capture the returns on their investments in training and innovation despite California’s ban on noncompetes because stock options generate a retention incentive that offsets employees’ incentive to free ride on these investments. However, unlike noncompete agreements, stock options induce retention in a highly selective manner: they temporarily suppress the mobility of employees of successful private companies (because, due to tax considerations, employees holding valuable options wait for a liquidity event, such as an initial public offering or acquisition, to cash out), but they do not limit the earning potential and mobility of laid-off employees and of employees of unsuccessful companies (whose stock options are virtually worthless). Stock options thus create an efficient breach mechanism that channels employees of less successful firms toward more promising ones and prevents inefficient retention. The paper also explores the crucial role of liquidity in the constant development of start-up ecosystems. Due to the retention effect of valuable but illiquid equity grants, I argue that companies’ current tendency to delay holding liquidity events might overly restrict the mobility of employees of large private companies and impair the talent allocation mechanism that gave Silicon Valley its competitive edge.