The invention relates to a liquid-crystalline medium, preferably having a nematic phase and dielectric anisotropy of 0.5 or more, which comprises one or more compounds of formula Y in which the parameters have the meanings given in the text, to the use thereof in an electro-optical display, particularly in an active-matrix display based on the IPS or FFS effect, to displays of this type which contain a liquid-crystalline medium of this type, and to the use of the compounds of formula Y for the improvement of the transmission and/or response times of a liquid-crystalline medium which comprises one or more additional mesogenic compounds.