  We classify thick subcategories of the $\infty$-categories of perfect modules
over ring spectra which arise as functions on even periodic derived stacks
satisfying affineness and regularity conditions. For example, we show that the
thick subcategories of perfect modules over $\mathrm{TMF}$ are in natural
bijection with the subsets of the underlying space of the moduli stack of
elliptic curves which are closed under specialization.
