  The intersection of topology and magnetism represents a new playground to
discover novel quantum phenomena and device concepts. In this work, we show
that a van der Waals compound MnSb$_{1.8}$Bi$_{0.2}$Te$_4$ exhibits a
ferromagnetic ground state with a Curie temperature of 26 K, in contrast to the
antiferromagnetic order previously found for other members of the Mn(Sb,
Bi)$_2$Te$_4$ family. We employ magneto-transport, bulk magnetization and
neutron scattering studies to illustrate the magnetic and electrical properties
of MnSb$_{1.8}$Bi$_{0.2}$Te$_4$ and report on the observation of an unusual
anomalous Hall effect. Our results are an important step in the synthesis and
understanding of ferromagnetic topological insulators.
