South African billionaire Johann Rupert has seen his net worth increase by more than $400 million in the first week of 2023, following a $1.09-billion decline in 2022,

Rupert, who is the wealthiest man in South Africa and the second-richest man in Africa, primarily derives his wealth from his 9.14-percent stake in Richemont, a Swiss luxury goods holding company.

Richemont owns a diverse portfolio of premium brands, including Chloe, Dunhill, Alaa, Cartier, and Delvaux.

According to the Bloomberg Billionaires Index, which tracks and compares the fortunes of the world’s 500 wealthiest individuals, the leading South African billionaire has seen his net worth rise from $10.9 billion to $11.4 billion since the start of the new year.

The increase in Rupert’s net worth can be attributed to the rise in Richemont’s shares, as investors expect the luxury goods company to deliver strong financial results at the end of the first nine months of its 2023 fiscal year.

This optimism is based on Richemont’s impressive performance in the first half of its current fiscal period, with profits rising by more than 40 percent from €1.5 billion ($1.55 billion) in the same period in 2022 to €2.1 billion ($2.17 billion) at the end of the first six months of 2023.

This builds on the company’s strong results in 2022 when profits increased by 61 percent from €1.289 billion ($1.36 billion) in 2021 to €2.08 billion ($2.2 billion).

As a result of the recent increase in shares of the luxury goods group on the Swiss and Johannesburg stock exchanges, the market value of Rupert’s 9.14-percent stake in the company has risen from $7.71 billion to $8.37 billion.

The bump in share value has propelled the South African billionaire to the rank of 161st richest person in the world, surpassing Goh Cheng Liang, a Singaporean billionaire businessman who owns a majority stake in Nippon Paint, the largest paint manufacturer in Asia.