Magnetoconductance across permalloy/InAs(2DES)/permalloy double junctions in the ballistic limit is examined within the transfer-matrix formalism. We take into account Rashba spin–orbit interaction in the semiconductor as well as oblique modes in devices of finite widths and calculate conductance ratios ΔG/Ḡ between distinct geometries of the magnetizations in the source and drain electrodes. The appropriate spin-dependent boundary conditions yield magnetoconductance ratios ΔG/Ḡ of up to 1% and Fabry–Pérot type interferences.