I analyze the case marking (nominative vs. partitive) and quantification of the Finnish existential S argument (S_e). I focus on S_e arguments quantified by mass quantifiers (e.g. paljon ‘much’) and number quantifiers (e.g. usea ‘many’). I discuss grammatical, semantic and discourse functions of the S_e argument, with an emphasis on the aspectual and quantificational meanings expressed by the construction. I argue that a quantified S_e designates a bounded quantity even when marked with the partitive case, which otherwise expresses unbounded quantity. This has important repercussions to the clause-level aspectual meaning of the existential construction, especially in uses where the aspectual profile of the clause is based on nominal aspect and thus on the quantity expressed by the S_e