Two-component mixtures of sieved glass beads (2.2, 3.1 and 4.65 mm) were fluidized by upward concurrent flows of air and water in two vertical columns, one of 7 cm diameter and 4.85 m height, and the other of 15 cm diameter and 2.7 m height. After steady-state operation, axial distributions of gas and solid holdups were measured by sectioning the whole column simultaneously with horizontal plates. When solid particles were fluidized at low liquid velocity and high gas velocity, an inverted segregation whereby small particles became concentrated below large particles was observed at a region where the total solid holdup was larger than 0.4. The axial holdup profile of each component of solid particles was described with a one-dimensional sedimentation-dispersion model. Inverted and normal segregation patterns calculated from the model were in agreement with experimental ones over an entire column consisting of dense and dilute regions.