Michelson interferometers have been routinely used in various applications ranging from testing optical components to interferometric time-resolved spectroscopy measurements. Traditionally, plate beamsplitters are employed to redistribute radiation between the two arms of an interferometer. However, such an interferometer is susceptible to relative phase fluctuations between the two arms resulting from vibrations of the beamsplitter. This drawback is circumvented in diffraction-grating-based interferometers, which are especially beneficial in applications where highly stable delays between the replica beams are required. In the vast majority of grating-based interferometers, reflective diffraction gratings are used as beamsplitters. Their diffraction efficiency, however, is strongly wavelength dependent. Therefore transmission-grating interferometers can be advantageous for spectroscopy methods, since they can provide high diffraction efficiency over a wide spectral range. Here, we present and characterize a transmission grating-based Michelson interferometer, which is practically dispersion-free, has intrinsically high symmetry and stability and moderate throughput efficiency, and is promising for a wide range of applications.