  We report on the status of our calculation of the hadronic matrix elements
for neutral $B$-meson mixing with asqtad sea and valence light quarks and using
the Wilson clover action with the Fermilab interpretation for the $b$ quark. We
calculate the matrix elements of all five local operators that contribute to
neutral $B$-meson mixing both in and beyond the Standard Model. We use MILC
ensembles with $N_f=2+1$ dynamical flavors at four different lattice spacings
in the range $a \approx 0.045$--$0.12$~fm, and with light sea-quark masses as
low as 0.05 times the physical strange quark mass. We perform a combined
chiral-continuum extrapolation including the so-called wrong-spin contributions
in simultaneous fits to the matrix elements of the five operators. We present a
complete systematic error budget and conclude with an outlook for obtaining
final results from this analysis.
