  We study instanton corrections to four-point correlation correlation function
of half-BPS operators in $\mathcal N=4$ SYM in the light-cone limit when
operators become null separated in a sequential manner. We exploit the relation
between the correlation function in this limit and light-like rectangular
Wilson loop to determine the leading instanton contribution to the former from
the semiclassical result for the latter. We verify that the light-like
rectangular Wilson loop satisfies anomalous conformal Ward identities
nonperturbatively, in the presence of instantons. We then use these identities
to compute the leading instanton contribution to the light-like cusp anomalous
dimension and to anomalous dimension of twist-two operators with large spin.
