The possibility of breaking the electroweak symmetry by the running of the Higgs quartic coupling without mass term is explored. It can be done by scalar fields with large couplings to the Higgs field and the model can be extended to be perturbative up to the Planck scale. Higgs self couplings are significantly enhanced and the deviation from the Standard Model can be probed by measuring Higgs pair production. The scalars and Higgs system also provides an interesting setup for studying unstable particles near threshold. The threshold singularity is reexamined and the meaning of mass and width for unstable particles is discussed.