ABSTRACT. We consider a family˘Em(D, M )¯of holomorphic bundles constructed as follows: to any given M ∈ GLn(Z), we associate a "multiplicative automorphism" ϕ of (C * ) n . Now let D ⊆ (C * ) n be a ϕ-invariant Stein Reinhardt domain. Then Em(D, M ) is defined as the flat bundle over the annulus of modulus m > 0, with fiber D, and monodromy ϕ.We show that the function theory on Em(D, M ) depends nontrivially on the parameters m, M and D. Our main result is thatwhere ρ(M ) denotes the max of the spectral radii of M and M −1 .As corollaries, we: -obtain a classification result for Reinhardt domains in all dimensions; -establish a similarity between two known counterexamples to a question of J.-P. Serre; -suggest a potential reformulation of a disproved conjecture of Siu Y.-T.Let D be a Stein manifold. We say that D belongs to S when: for any Stein manifold B and any locally trivial bundle E → B, the manifold E is also Stein. A famous question of Serre can be formulated as: "Are all manifolds in S?" Skoda answered it in the negative, by proving that C 2 ∈ S (cf. Here we study holomorphic functions on a family of bundles {E m (D, M )} over annuli, depending on a non necessarily bounded Reinhardt domain Date: September 24, 2017. zaffran@fudan.edu.cn Fudan University, Shanghai. Academia Sinica, Taipei.