We generalize the results for statistical functionals given by [Fernholz, 1983] and [Serfling, 1980] to M estimates for samples drawn for an ergodic and stationary martingale sequence. In a first step, we take advantage of some recent results on the uniform convergency of the empirical...

We proof that Hadamard differentiability in addition with usual assumptions on the loss function for M estimates implies differentiability in quadratic mean. Thus both concepts are exchangeable.