What is it that makes events difficult to predict? Starting with the assumption that unpredictability is commensurate with complexity, the article examines a highly complex process of discontinuous change, defined as ‘sudden convergence’—spontaneous, momentary correlation between components or preferences that were heretofore unrelated. This process is illustrated through the rise of ‘Ataka’—a nationalist–populist party in Bulgaria, which attained 9 per cent of the parliamentary vote shortly after its creation. Making use of multiple data sources, the analysis finds a highly heterogeneous support base of ‘Ataka’, with diverse protest rationales abruptly realigned in the same political corner in seemingly haphazard manner and with little indication for strategic oversight. A complex amalgam of interests is forged under substantial ambiguity. The analysis contributes to understanding a general problem—how individual preferences that are not supposed to be correlated become suddenly tied together, giving rise to events that severely strain our predictive capabilities, such as mass protest or economic crises.