Since their emergence a decade ago, global university rankings have become a powerful force in higher education internationally. The majority of research studies on global rankings have examined the effects at institutional and national levels. This study offers a valuable perspective on the ways rankings (and other international benchmarks) are deployed at the intra-sector level, by UK higher education "mission groups", to support different policy positions. The concept of object in activity theory is used to problematize the analysis. Critical discourse analysis is used as a methodological orientation to study the ways global rankings mediate the object in this context. The findings contribute to the current debate on whether rankings are promoting isomorphism in higher education sectors nationally, illustrating a differentiated engagement with rankings in the UK context. The relevance of the findings for policy-makers and institutional managers is discussed.