The shear-stability of inverse latexes (IL) during their polymerization process is studied. The IL is made of water droplets containing a copolymer of acrylamide and dimethyl-aminoethyl-methylenechloride emulsified in a paraffin oil. It is found for the first time that the shear stability of the ILs is a nonmonotonic function of the monomer conversion. At low conversions the shear stability increases as the conversion increases, but at a certain conversion value it reaches a local maximum and then decreases with conversion. Moreover, at the final stage of the conversion, the shear stability can increase again. A proper interpretation of this behavior is proposed and related to the combined effects of the polymer properties, fractal aggregation, and coalescence. (C) 2015 American Institute of Chemical Engineers