The variable sdB known as V46 in the globular cluster M4 has remained enigmatic since its discovery almost 10 years ago .
We present here radial velocity measurements obtained from medium-resolution VLT/FORS2 spectra that show variations at twice the period of the luminosity changes .
This implies that the system is an ellipsoidal variable .
Unlike the other sdB binaries of this nature , the fundamental parameters of this star we derive suggest that it lies below the Zero Age Extreme Horizontal Branch .
From the cluster distance and the gravity we determine the mass of V46 to be \sim 0.19M _ { \odot } .
This is too low to sustain core helium burning .
From the mass function we derive a lower limit for the companion of only 0.26M _ { \odot } .
We discuss the star ’ s origin in the context of close binary evolution in the field and globular clusters .