i will present some recent joint work with sorin popa where we show that, under the continuum hypotheses, any ultraproduct ii$_1$ factor contains more than continuum many mutually disjoint singular masas. in other words, the singular abelian rank of any ultraproduct ii$_1$ factor $m$, $\text{r}(m)$, is larger than $\mathfrak{c}$. moreover, if the strong continuum hypothesis $2^\mathfrak{c}=\aleph_2$ is assumed, then $\text{r}(m) = 2^\mathfrak{c}$. more generally, these results hold true for any ii$_1$ factor $m$ with unitary group of cardinality $\mathfrak{c}$ that satisfies the bicommutant condition $(a_0'\cap m)'\cap m=m$, for all $a_0\subset m$ separable abelian.