Theoretical predictions for $b\to s{\mu }^{+}{\mu }^{-}$ decays

I review the state of the art of the theoretical calculations for decays mediated by $b\to s{\mathrm{\ell }}^{+}{\mathrm{\ell }}^{-}$ transitions, for $\mathrm{\ell }=e,\mu$. I focus on the predictions of observables in $B\to K{\mu }^{+}{\mu }^{-}$, $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$, and $B_s\to \phi {\mu }^{+}{\mu }^{-}$ decays, as many of these predictions are in tension with the corresponding experimental measurements. I also briefly discuss the ${\mathrm{\Lambda }}_b\to \mathrm{\Lambda }{\mu }^{+}{\mu }^{-}$ decay and present a new calculation for this channel. Special emphasis is placed on the non-local contributions, as they are the largest systematic uncertainties in these decays. The current theoretical calculations for $b\to s{\mu }^{+}{\mu }^{-}$ decays are not able to explain the tensions with the experimental measurements.