In the presence of peroxide, hydrogen chloride and hydrogen iodide do not give anti-Markovnikov's addition to alkenes because:

In the presence of peroxide, hydrogen chloride and hydrogen iodide do not give anti Markovnikov's addition to alkenen because : both are highly ionic, one is oxidising and the other is reducing, one of the steps is endotherrmic in both the cases, all the steps is exothermic in both the reactions