Africa’s biggest initial public offering has already secured enough commitments from Nigerian and retail investors to meet its fundraising target, according to people familiar with the matter.

That’s setting up a likely allocation squeeze as international investors race to secure a stake in Aliko Dangote’s almost $50 billion refinery business, said the people who asked not to be identified because the process is ongoing.

The offering has attracted about $1.5 billion to $1.6 billion of fully funded commitments from domestic and retail investors alone, they said.

That means Dangote Petroleum Refinery and Petrochemicals FZE — whose oil-processing complex in Lagos is the continent’s largest — has effectively reached its funding target before accommodating international demand, they said. A spokesman for Dangote declined to comment.

The company is expected to make use of an additional 30% over-allotment option, largely to create room for overseas investors, said the people. Even with the expanded allocation that would take the fundraising to about $2.1 billion, demand from foreign investors could exceed available stock, they said.

Africa’s richest man extended the closing date for IPO applications by two weeks to Oct. 27 as his team criss-crossed the continent to provide structures to broaden participation beyond Nigeria and deepen capital-market integration.

In a first, investors from all 54 African countries asked for allocations, said the people. All together, investors from 119 nations applied to gain access to the IPO at the time of writing, they said.

The offering also includes nominee structures for Standard Bank Group Ltd., Egypt and Ethiopia, as well as global depository receipts being sold by stock exchanges in Kenya and Botswana.

If demand significantly outstrips supply, Dangote could choose to sell part of his stake to investors that fail to secure allocations in the IPO through a secondary sale, said the people.

Any secondary offering would depend on Dangote’s assessment of the final order book, and no decision on a secondary sale has been made, they said.

“We have more than reached our target,” the billionaire said in Gaborone, Botswana, on Oct. 14, adding that the refinery has had interest of “more than three times or four times what we are looking for.”Dangote’s facility is one of Africa’s most strategic industrial assets and provides a rare, large-scale equity transaction for international investors seeking exposure to the continent.

The deal also proves that significant allocation can be secured from African investors, rather than depending on Wall Street or London for investment in local assets.