A multistage aqueous emulsion polymer comprising from 88% to 98% by dry weight, based on total dry weight of the multistage aqueous emulsion polymer, of a first polymer core; and from 2% to 12% by dry weight, based on total dry weight of the multistage aqueous emulsion polymer, of a second polymer shell, wherein the first polymer core and the second polymer shell each independently comprises, as polymerized units, one or more ethylenically unsaturated nonionic monomers, wherein the second polymer shell further comprises, as polymerized units, from 20% to 60% by dry weight, based on total dry weight of the second polymer shell, of an acid monomer, wherein said acid monomer is, as polymerized units, from 1.1% to 4.2% by dry weight, based on total dry weight of the multistage aqueous emulsion polymer. An aqueous coating composition comprising said multistage aqueous emulsion polymer.
