(57) An SMT-type transformer comrprises a ferrite core formed of two complementary portions mirror-symmetrically joined to one another, and a body including a primary and a secondary winding supported on one of the legs of the core. The two core portions are retained in the assembled condition by a retaining cage (7) preferably formed of a ferromagnetic material and having a top surface (8) engaging one core portion (5), and a plurality of legs (9) extending from the top surface and having end portions (10, 11) adapted to be bent into angagement with the other core portion (6). Integrally foremd with the legs are annular portions (12) surrounding the winding body (1) so as to constitute a short-circuit winding therearound.