We predict that accounting conservatism influences insiders' opportunities to speculate on good and bad news, and thus, insider trading profitability. We find that greater conditional (unconditional) conservatism is associated with lower (higher) insiders' profitability from sales. We find limited evidence that conservatism influences profitability from purchases. These findings are consistent with our hypotheses on the different informational roles of conditional and unconditional conservatism, and on the asymmetric influence of conservatism over the opportunities to speculate on good versus bad news. Our research design takes into consideration the endogenous nature of insiders' trading and conservatism. The results are robust to different measures of conservatism and a number of additional analyses.