The present invention relates to a composition comprising a) an aqueous dispersion of polymer particles and b) a hydrophobically modified poly(oxyalkylene-urethane) rheology modifier having a 1) backbone; and 2) a hydrophobic portion represented by Fragment I: where R and R1 are defined herein. The composition is useful as an aqueous coating formulation that exhibits a highly shear thinning rheology profile suitable for spray applications to provide high sag resistance without adverse impact on gloss or corrosion resistance.