Can a supervoid explain the Cold Spot?
  The discovery of a void of size $\sim200\;h^{-1}$Mpc and average density
contrast of $\sim-0.1$ aligned with the Cold Spot direction has been recently
reported. It has been argued that, although the first-order integrated
Sachs-Wolfe (ISW) effect of such a void on the CMB is small, the second-order
Rees-Sciama (RS) contribution exceeds this by an order of magnitude and can
entirely explain the observed Cold Spot temperature profile. In this paper we
examine this surprising claim using both an exact calculation with the
spherically symmetric Lema\^itre-Tolman-Bondi metric, and perturbation theory
about a background Friedmann-Robertson-Walker (FRW) metric. We show that both
approaches agree well with each other, and both show that the dominant
temperature contribution of the postulated void is an unobservable dipole
anisotropy. If this dipole is subtracted, we find that the remaining
temperature anisotropy is dominated by the linear ISW signal, which is orders
of magnitude larger than the second-order RS effect, and that the total
magnitude is too small to explain the observed Cold Spot profile. We calculate
the density and size of a void that would be required to explain the Cold Spot,
and show that the probability of existence of such a void is essentially zero
in $\Lambda$CDM. We identify the importance of \emph{a posteriori} selection
effects in the identification of the Cold Spot, but argue that even after
accounting for them, a supervoid explanation of the Cold Spot is always
disfavoured relative to a random statistical fluctuation on the last scattering
surface.
