More than four billion shares in Aliko Dangote’s giant oil refinery, representing just over 3% of the company, went on sale Monday in Africa’s biggest-ever offering of its kind. The minimum purchase was 10 shares for about $4 (£3), drawing enthusiastic participation from Nigerians and overwhelming investment apps on the first day. The IPO (initial public offering) was intended to give ordinary workers a stake in the refinery, which now processes around 700,000 barrels of crude a day and supplies much of Nigeria’s domestic demand. Younger investors’ growing use of mobile trading platforms, cryptocurrencies and digital savings products helped drive interest, although analysts warned that shares can fall and that crude supply, operational, regulatory and demand risks could affect the business. Dangote is raising money to finance the refinery’s growth.