  In [Ma1] S. Ma established a bijection between Fourier--Mukai partners of a
K3 surface and cusps of the K\"ahler moduli space. The K\"ahler moduli space
can be described as a quotient of Bridgeland's stability manifold. We study the
relation between stability conditions $\sigma$ near to a cusp and the
associated Fourier--Mukai partner Y in the following ways. (1) We compare the
heart of $\sigma$ to the heart of coherent sheaves on Y. (2) We construct Y as
moduli space of $\sigma$-stable objects.
  An appendix is devoted to the group of auto-equivalences of the derived
category which respect the component $Stab^\dagger(X)$ of the stability
manifold.
