  Higgs-boson pair production at hadron colliders is dominantly mediated by the
loop-induced gluon-fusion process $gg\to HH$ that is generated by heavy top
loops within the Standard Model with a minor per-cent level contamination of
bottom-loop contributions. The QCD corrections turn out to be large for this
process. In this note, we derive the top-Yukawa-induced part of the electroweak
corrections to this process and discuss their relation to an effective
trilinear Higgs coupling with integrated out top-quark contributions.
