The Nigerian billionaire, Abdulsamad Rabiu, is quickly approaching a historic financial milestone, as Nigeria's second-richest man and Africa's second-richest individual currently has a net worth of $19.7 billion, according to the Bloomberg Billionaires Index.

The most recent appraisal represents a $606 million boost in his fortune, bringing his year-to-date gain to an astonishing $9.53 billion and putting him just $300 million away from the elite $20 billion threshold, a feat only one African, Aliko Dangote, has accomplished.

Dangote presently leads the continent's wealth rankings, with a net worth of $36.7 billion, cementing Nigeria's position at the top of Africa's billionaires.

Rabiu's wealth increase has been one of the most astounding stories in world business this year.

In March, he made one of his most significant net worth leaps, adding $4.47 billion and increasing his fortune from $10.7 billion to $14.6 billion.