In this talk we will review the appearance of an infinite dimensional symmetry algebra of tree level scattering amplitudes of N=4 super Yang-Mills theory, known as the Yangian of psu(2,2 4). It arises through the commutation of standard superconformal and the recently discovered dual superconformal symmetries of scattering amplitudes. At the loop level the conformal and dual conformal symmetry is destroyed by infrared divergencies. The present challenge is whether it may be repaired. We point out a novel IR regularization based on a suitable Higgsing of the theory, which is natural from the dual string perspective. It turns out that in this regularization an extended conformal symmetry of the loop amplitudes arises, which remains free of anomalies.