Let X be a CW complex with a continuous action of a topological group G. We
show that if X is equivariantly formal for singular cohomology with
coefficients in a field, then so are all symmetric products of X and in fact
all its Gamma-products. In particular, symmetric products of quasi-projective
M-varieties are again M-varieties. This generalizes a result by Biswas and
D'Mello about symmetric products of M-curves. We also discuss several related
questions.Comment: 9 pages; minor change