  We present an update to the NNLL RG-improved QCD prediction of top-antitop
production in electron-positron annihilation at threshold. It includes for the
first time a complete NNLL resummation of ultrasoft logarithms, which are
dominant at this order and give a sizable correction. The renormalization scale
dependence of the total resonance cross section decreases substantially
compared to earlier predictions, where the ultrasoft logarithms were included
only partially.
