A counterexample to vanishing conjectures for negative K-theory

In a 2006 article Schlichting conjectured that the negative K–theory of any abelian category must vanish. This conjecture was generalized in a 2019 article by Antieau, Gepner and Heller, who hypothesized that the negative K–theory of any category with a bounded t–structure must vanish. Both conjectures will be shown to be false.