Let k be a complete non-archimedean field (non trivially valued). Given a
reductive k-group G, we prove that hyperspecial subgroups of G(k) (i.e.
those arising from reductive models of G) are maximal among bounded
subgroups. The originality resides in the argument: it is inspired by the case
of GLn and avoids all considerations on the Bruhat-Tits building of
G.Comment: To appear at "Annales de l'Institut Fourier". This version avoids
completely Berkovich geometr