 The IPC consists of a sample of 35 shares weighted according to their market capitalisation.Heavy hitters are America Telecom, the holding company that manages Latin America's largest mobile company, América Móvil; Telefonos de Mexico, Mexico's largest telephone company; Grupo Bimbo, world's biggest baker; and Wal-Mart de México, a subsidiary of the US retail giant.The makeup of the IPC is adjusted every six months, with selection aimed at including the most liquid shares in terms of value, volume and number of trades.