Semi-invertible extensions of C⁎-algebras

We prolong the list of C⁎-algebras which have the property that all extensions by a stable C⁎-algebra are semi-invertible. In particular, it is shown to include group C⁎-algebras, both reduced and full, of certain amalgamated free products of amenable groups, as well as all free products of nuclear C⁎-algebras with amalgamation over a common nuclear C⁎-subalgebra.