To analyze the evolution of quantitative easing’s (QE) and tightening’s (QT) effects across consecutive announcements, we focus on their unexpected component. Treasury yield sensitivities to QE and QT supply surprises do not fall monotonically over time, thus later announcements seemed to remain powerful; yield sensitivities to QT surprises are on average larger than sensitivities to QE surprises, implying supply effects did not diminish during periods of market calm amid economic expansion; finally, yield sensitivities are amplified by the amount of interest-rate uncertainty prevailing before the announcement, implying that turning points in the balance sheet policy tended to elicit larger reactions.