MTN's largest shareholder, the Public Investment Corporation, said yesterday it wants more people to take responsibility for the $5.2-billion (R74.3-billion) fine imposed on the company by Nigerian authorities. Sifiso Dabengwa announced his resignation as MTN CEO yesterday, taking personal responsibility for the fine imposed for failing to cut off users with unregistered sim cards.PIC CEO Daniel Matjila said: "A lot more people need to take collective responsibility for the fine that was imposed on MTN Nigeria for alleged failure to comply with regulatory requirements in that country."The PIC manages the South African government pension fund.MTN asked its former boss to take temporary charge of Africa's biggest mobile telecoms company after Dabengwa quit.Current non-executive chairman Phuthuma Nhleko was named executive chairman of MTN for a period of up to six months.Nigeria is MTN's largest market and contributes more than a third of its revenue.MTN said it was continuing talks with authorities in Nigeria about decreasing the onerous fine, which would wipe away a fifth of the value of the company.The Nigerian Communications Commission has been pushing companies to verify the identity of their subscribers because of fears that unregistered sims were being used for criminal activity in a country facing insurgency by Islamic militant group Boko Haram.Shares in MTN have slid by nearly 20% since October 26 when the charge was first reported, but traded 2.2% higher after Nhleko's appointment.In his nine years as CEO Nhleko was largely credited with the company's expansion outside its home market.Momentum SP Reid analyst Sibonginkosi Nyanga said: "He's the guy who built MTN into what it is."MTN also faces a Johannesburg stock exchange investigation of the timing of its announcement of the penalty.Ratings agencies Moody's and Fitch lowered MTN's credit rating outlook to "negative" last month, flagging the risk of significant cash outflow and the likely damage to the Nigerian business due to lengthy talks.The ANC has said it is concerned about the fine but that this would not affect relations between the continent's two biggest economies...