We present constraints on the evolution of the virial to stellar mass ratio of galaxies with high stellar masses in the redshift range 0.2 < z < 0.8 , by comparing weak lensing measurements of virial mass M _ { vir } to estimates of stellar mass M _ { star } from COMBO-17 .
For a complete sample of galaxies with \log ( M _ { star } / M _ { \odot } ) > 10.5 , where the majority show an early-type morphology , we find that the virial mass to stellar mass ratio is given by M _ { vir } / M _ { star } = 53 ^ { +13 } _ { -16 } .
Assuming a baryon fraction from the concordance cosmology , this corresponds to a stellar fraction of baryons in massive galaxies of \Omega _ { b } ^ { * } / \Omega _ { b } = 0.10 \pm 0.03 .
Analysing the galaxy sample in different redshift slices , we find little or no evolution in the virial to stellar mass ratio , and place an upper limit of \sim 2.5 on the growth of massive galaxies through the conversion of gas into stars from z = 0.8 to the present day .