Strategic Tanking in Stable Matching Markets

Abstract

Motivated by a broad literature in psychology, organizational behavior, and matching markets, we introduce strategic tanking: an agent deliberately makes themselves less attractive to selected potential partners in order to improve their eventual assignment. Unlike traditional manipulation in stable matching, a tanker does not misreport whom they prefer; instead, they influence how others rank them. We show that tanking has a striking connection to classical preference manipulation. Cutoff tanking, in which an agent tanks with every potential partner below a chosen threshold, has exactly the same effect on the stable set as truncating one's own preference list at that threshold. Thus an agent can reproduce the power of a classical truncation while leaving their own preferences unchanged and every match acceptable. Arbitrary tanking, however, can go substantially further: under proposer-deferred acceptance, tanking equilibria can lie outside the sincere stable set. More broadly, whenever the sincere stable set contains multiple matchings, profitable strategic behavior remains available through either traditional preference manipulation or tanking, even when one side is restricted to honestly reporting their own preferences.