We study the optimal levels of advertising and promotion budgets in dynamic markets with brand equity as a mediating variable. To this end, we develop and estimate a state-space model based on the Kalman filter that captures the dynamics of brand equity as influenced by its drivers that include a brand's advertising and sales promotion expenditures. By integrating the Kalman filter with the random coefficients logit demand model, our estimation allows us to capture the dynamics of brand equity as well as model consumer heterogeneity using store-level data. Using these demand model estimates, we determine the Markov Perfect Equilibrium advertising and promotion strategies. Our empirical analysis is based on store-level scanner data in the orange juice category, which comprises two major brandsTropicana and Minute Maid. The calibration of the demand model reveals that sales promotions have a significant positive effect on consumers' utility and induce consumers to switch to the promoted brand. However, there is also a negative effect of promotions on brand equity that carries over from period to period. Overall, we find that while sales promotions have a net positive impact both in the short-term and in the long-term, the implied total elasticity including the long-term effect is smaller than the short-term elasticity. Correspondingly, we expect myopic decision-makers to allocate higher than optimal expenditures to sales promotions. Our results from the supply side analysis reveal that the equilibrium forward-looking promotion levels are higher for Minute Maid, the brand for which the adverse long-term effect of promotions is lower. However, the observed promotion levels are higher for Tropicana compared to Minute Maid, a result consistent only with the myopic case. Further, our results reveal that the actual promotion levels for both brands are higher than the optimal budgets for the forward-looking as well as the two-year planning horizon scenarios. Hence, it may be profitable for both brands to reduce their promotion levels. The equilibrium forward-looking advertising levels are higher for Tropicana, the brand that has a higher responsiveness to advertising. Further, the optimal forward-looking advertising levels are higher than the optimal budgets for the myopic as well as the two-year planning horizon scenarios. However, these levels are higher than the actual advertising expenditures for both brands. Hence, it may be optimal for both brands to reduce their advertising levels.