This chapter explains the risk parity portfolio models that became popular after the great financial crisis in 2008 as a type of all weather portfolios. These types of portfolios, unlike return-risk trade-off models, split the risk among assets instead of splitting the budget among assets; for this reason these models are also called risk budgeting portfolio models. They are mainly used to aggregate several kinds of strategies because by their design they assign a weight to all assets and are not suited for a large number of assets. These models are more robust than classic return-risk trade-off portfolios because their optimal asset allocation is closer to the equally weighted portfolio than to the efficient frontier.