Calculations of high multiplicity Higgs amplitudes exhibit a rapid growth that may signal an end of perturbative behavior or even the need for new physics phenomena. As a step towards this problem we consider the quantum mechanical equivalent of 1 → n scattering amplitudes in a spontaneously broken φ 4 -theory by extending our previous results on the quartic oscillator with a single minimum [1] to transitions n|x|0 in the symmetric double-well potential with quartic coupling λ. Using recursive techniques to high order in perturbation theory, we argue that these transitions are of exponential form n|x|0 ∼ exp (F (λn)/λ) in the limit of large n and λn fixed. We apply the methods of "exact perturbation theory" put forward by Serone et al. in [2,3] to obtain the exponent F and investigate its structure in the regime where tree-level perturbation theory violates unitarity constraints. We find that the resummed exponent is in agreement with unitarity and rigorous bounds derived by Bachas [4].