Thus, over time, microfinance institutions can contribute to a more robust financial system. Initially, microfinance institutions may serve a relatively small portion of the poor in a financially developing society. Given low levels of bank penetration, however, their potential customer base is potentially large in these societies. If the microfinance institutions can attract sufficient capital and operate in a financially sound manner, they have the potential to become quite significant players in providing financial services and credit. As these institutions grow, some of them become better able to serve broader functions of financial intermediation. Moreover, as the microfinance sector grows, mainstream financial institutions may be better able, and more willing, to serve a broader segment of society. These institutions may begin to partner with each other, and the various financial sectors of economy may move to a more integrated financial system.