  We investigate heavy-light four-quark systems $ud\bar b \bar b$ with bottom
quarks of finite mass which are treated in the framework of NRQCD. We focus on
$I(J^P)=0(1^+)$, where we recently found evidence for the existence of a
tetraquark state using static bottom quarks. Furthermore, we report on an
investigation of the $u \bar d b \bar b$ four-quark system with quantum numbers
$I(J^P)=1(1^+)$ again using static bottom quarks.
