During daily encounters, it is inevitable that people take risks. Investigating the sequential processing of risk hazards involve expectation formation about outcome contingencies. The present study aimed to explore risk behavior and its neural correlates in sequences of decision making, particularly in old age, which represents a critical period regarding risk-taking propensity. The Balloon Analogue Risk Task was used in an electrophysiological setting with young and elderly age groups. During the task each additional pump on a virtual balloon increased the likelihood of a balloon burst but also increased the chance to collect more reward. Event-related potentials associated with rewarding feedback were analyzed based on the forthcoming decisions (whether to continue or to stop) in order to differentiate between states of expectation towards gain or loss. In the young, the reward positivity ERP component increased as a function of reward contingencies with the largest amplitude for rewarding feedback followed by the decision to stop. In the elderly, however, reward positivity did not reflect the effect of reward structure. Behavioral indices of risk-taking propensity suggest that the performance of the young and the elderly were dissociable only with respect to response times: The elderly was characterized by hesitation and more deliberative decision making throughout the experiment. These findings signify that sequential tracking of outcome contingencies has a key role in cost-efficient action planning and progressive expectation formation.Keywords: Aging; Decision making; Feedback-related ERPs; Reward positivity; Risk-taking behavior Whether we are aware of the fact or not, risk-taking behavior occurs more frequently during our everyday actions than generally thought. Besides those simple and common examples like taking only one more drink before driving, a temporary excursion from one's self-regulatory goals, i.e., risking the long-term goals for short-term advantages such as making a cheat in a diet, can be considered as a more complex form of 'gambling' [1]. Risk-taking behavior can be defined as a decision making propensity motivated by gain reward beside the possible opportunity to lose [2][3][4]. Since natural circumstances usually include continuous fluctuations in risk, the ability of making decisions based on the acquisition of action-outcome contingencies is an essential part of adaptive risk behavior [5]. In particular, old age represents a critical period due to substantial neurocognitive changes having an effect on both frontal cortical and subcortical brain areas known to be involved in decision making [6,7]. The question remains, however, whether there is a specific inability of the acquisition of relevant information behind the possibly reduced decision quality of the elderly.From the perspective of self-report questionnaires, elderly are characterized by higher risk-avoidance tendency [8]. However, regarding risk behavior, results show evidence for both normal and altered patterns of ...