The standard model (SM) production of four top quarks (t t ¯ t t ¯) in proton–proton collisions is studied by the CMS Collaboration. The data sample, collected during the 2016–2018 data taking of the LHC, corresponds to an integrated luminosity of 137fb-1 at a center-of-mass energy of 13TeV. The events are required to contain two same-sign charged leptons (electrons or muons) or at least three leptons, and jets. The observed and expected significances for the t t ¯ t t ¯ signal are respectively 2.6 and 2.7 standard deviations, and the t t ¯ t t ¯ cross section is measured to be 12.6-5.2+5.8fb. The results are used to constrain the Yukawa coupling of the top quark to the Higgs boson, yt, yielding a limit of |yt/ytSM|