An employee's MPF assets are fully vested, and are portable when the employee changes employers. Benefits that have accrued under the scheme of a former employer can be transferred to a scheme operated by the new employer. There are strict guidelines on the types of assets in the investment funds. However, MPF providers may offer more than one investment option constituted along the guidelines to its members through different funds, thus employees may build their own investment portfolio out of the funds provided by the provider chosen by their employers. Employees may elect on the asset allocation among different funds available from their providers, but may only do so for their part of the retirement contribution.