Black holes display universal behavior near extremality. One such feature is the late-time blowup of derivatives of linearized perturbations across the horizon. For generic initial data, this instability is regulated by backreaction, and the final state is a near-extremal black hole. The aim of this paper is to study the late time behavior of such black holes analytically using the weakly broken conformal symmetry of their near-horizon region. In particular, gravitational backreaction is accounted for within the Jackiw-Teitelboim model for near-horizon, near-extremal dynamics coupled to bulk matter.types of perturbation fields [14], [15], [16], [17], and in particular in [18] it was shown that a massless scalar displays Aretakis behavior on any extreme BH background. The picture arising from these studies is that the Aretakis behavior is a general feature of extremal BHs, in the following sense: the k-th transverse-to-the-horizon derivative of the perturbation, at late times on the horizon, behaves (no worse than 1 )where ∆ − is a negative k-independent, fixed non-universal constant. 2 A convenient way to repackage (1.2) (assuming an expansion in the radial coordinate) is to use the following ansatz for the field (assume a scalar field for simplicity):where F (z) is an arbitrary function which is smooth at z = 0. It is important to note that this type of behavior is consistent with the results of [20], which showed that for generic initial data in extremal RN the decay and blowup rates (1.2) are saturated (again, modulo the skip phenomenon described in footnote 1). Following [21] (see also [3]), plugging (1.3) into the 1+1 dimensional wave equation for each mode and considering the near-horizon, late-time limit reduces it to an ordinary differential equation for F (z), which yields a universal behavior for the field at late times near the horizon. For example, for the spherically symmetric mode (∆ − = −1) of the above discussed neutral massless scalar around extreme RN: 3, (1.4) at late times, where H 0 is interpreted as the ℓ = 0 Aretakis constant.Since the Aretakis analysis concerns linearized perturbations and involves blowup, one must ask whether and how gravitational backreaction becomes important. This was addressed in [22] numerically for spherically symmetric perturbations of a massless, neutral scalar field. The conclusions were that the instability persists under backreaction, and that for generic initial data, the BH approaches a new, non-extremal solution at late times, and this allows perturbations to exponentially decay at times of the order of the inverse temperature. This