The CEO and chairman of LVMH has lost $19.2 billion in net worth, according to the Bloomberg Billionaires Index.
He is now the third richest person in the world behind Elon Musk, the CEO of automaker Tesla, and Jeff Bezos, the founder of online retailer Amazon.
LVHM shares have plunged 14% in the last six months as it struggles amid low demand in the luxury goods sector.
The company posted a 1% year-on-year revenue growth in the second quarter, falling short of analyst’s estimates.
In the Asian market (excluding Japan), LVHM saw a year-on-year revenue fall of 10% in the first six months.
Other luxury brands such as Burberry, Richemont and Kering are also facing challenges in sales.
LVMH is the largest luxury company in the world. The company owns 70 fashion and cosmetics brands, such as Sephora, Tiffany & Co, Givenchy, Christian Dior, Dom Perignon, and Moët Hennessy.
Arnault has five children, all of whom work for LVMH. Arnault's goal is to consolidate his family's control over the world's largest luxury empire.