A search for direct pair production of top squarks, the hypothetical supersymmetric partner to the top quark, in proton-proton collisions is presented for two scenarios each requiring jets and a large transverse momentum imbalance. The CMS detector observed the proton-proton collisions which were generated by the LHC with a center- of-mass energy of 13 TeV. The two scenarios include, a “low ∆m” analysis targeting very small mass differences between the top squark and the neutralino, and a “high ∆m” analysis targeting topologies typical for larger mass splittings. Using data collected during operations in 2015 corresponding to an integrated luminosity of 12.9 /fb, no significant excess of events above the expected standard model background processes is observed. Exclusion limits are set in the context of simplified models of top squark pair production under various decay hypotheses.