Endogenous order and information aggregation

► Privately informed experts with heterogeneous expertise decide when to give advice and what advice to give under payoff externalities. ► Without forcing any order of speech, we obtain a result similar to the 'anti-seniority rule'. ► Under negative payoff externalities, all experts send a message together without any delay and a herd never arises. ► An incentive structure with positive payoff externalities gives rise to a herd led by the most precise expert with a delay in the disclosure of information.