  We compute two-loop electroweak corrections to Higgs boson pair and Higgs
plus jet production, taking into account all sectors of the Standard Model. All
diagrams with virtual top quarks are computed in an expansion for large top
quark mass up to order $1/m_t^8$ or more. We present analytic results for the
form factors and discuss the convergence properties. For the process $gg\to gH$
we also consider QCD corrections in the large-$m_t$ limit.
