Disclosed herein is an apparatus for forming sheath-and-core fibers, the apparatus comprising a series of stacked distribution plates comprising channels arranged to convey first and second fluidized polymers separately and comprising a restriction zone for distributing the second fluidized polymer around the first polymer as a sheath. Also disclosed is a method for forming such sheath-and-core fibers. The apparatus and method are well suited to forming sheath-and-core fibers having very low percentage of sheath component.