The net worth of South African billionaire Johann Rupert has taken a hit in December, according to data tracked by the Bloomberg Billionaire Index.

Rupert, who is the richest billionaire in South Africa and the second-wealthiest businessman on the African continent, recorded a $300 million slump in his wealth figures, from $10.9 billion to $10.6 billion. This decrease comes after a $1.76 billion surge in his net worth in November.

The market value of Rupert’s stake in Richemont, the luxury goods company of which he is chairman, decreased from $7.71 billion to $7.54 billion in December alone.

This was due to a 5.04 percent decrease in the company’s share price, from CHF123 ($131.8) per share on December 1 to CHF116.8 ($125.2) per share. The market value of his stake in investment holding Remgro Limited also decreased during this time.

The decrease in the market value of Rupert’s publicly traded assets has contributed to a year-to-date wealth loss of $1.38 billion. This makes Rupert one of the few African billionaires who has experienced a significant decline of over a billion dollars in the past year.

Analysts attribute the December drop in the market value of Richemont and Remgro to global economic uncertainty, which has been exacerbated by the rise in consumer prices, which continues to put pressure on luxury demand.

Despite this, Rupert remains optimistic about the future of his businesses, particularly Richemont, which he believes will continue to thrive in the luxury goods market.

In addition to his stakes in Richemont and Remgro, Rupert also has a significant presence in the healthcare industry through his involvement in Mediclinic International, a private hospital group based in South Africa, Namibia, Switzerland, and the United Arab Emirates.

Rupert’s investment firm, Remgro, owns 44.6 percent of Mediclinic, making it the largest hospital operator in South Africa. Recently, Mediclinic and a consortium led by Remgro reached an agreement to buy out Mediclinic’s outstanding shares.

The terms of the deal value the group’s entire issued and to be issued ordinary share capital at approximately £3.7 billion ($4.48 billion) with an implied enterprise value of around £6.1 billion ($7.4 billion).