Chu, the chief executive of financial services firm Kingston Financial Group and head of Macau VIP junket group Golden Resorts Group, is one of the most well-known business figures in the Chinese territory of Hong Kong.
The 60-year-old's stake in Kingston is now worth around $2.6 billion, down from $9.7 billion at the end of 2017, Thomson Reuters data showed.
Chu's Kingston, which she co-founded with her husband in 1992, has lost 73.3 percent so far this year, bringing its market value down to $3.47 billion on Thursday from $13.01 billion at the end of last year.
The slide followed a warning from Hong Kong's Securities and Futures Commission that Kingston had 20 shareholders who together controlled more than 91 percent of the listed company.
The market value of Chu's stake in Kingston has plunged after the warning in January.
Chu and Kingston were not immediately available for comment as phone calls went unanswered, while they did not respond to email requests for comment.
Chu's family has been involved in Macau's murky junket sector for over two decades. Her father, Wai Man Lee, a gambling industry veteran, founded a high roller room in the former Portuguese colony's Casino Lisboa, which belonged to local tycoon Stanley Ho.
Macau's VIP sector is reliant on the junket system - licensed middlemen who extend millions of dollars in credit to mainland gamblers and assume responsibility for loan repayment, often indelicately, authorities say.
Chu's links with Ho and Macau's gambling sector have bolstered her and Kingston's fortunes in the past due to soaring revenues in the world's biggest casino hub.
Kingston still runs its casino operations through Ho's SJM Holdings and owns Hotels Casa Real and Grandview. In its latest annual report, Kingston said the company faced strong competition in Macau leading to gaming revenue to fall 4 percent year-on-year.
Over the past several years, properties belonging to Chu and run by SJM have been overshadowed by newer and glitzier resorts opening on Macau's Cotai strip.
The majority of Kingston's debt funding is provided by Chu and her family, according to a report by Hong Kong-based activist investor David Webb.
Chu is also the executive chairman of Sincere Watch Ltd, directly holding 4.38 pct of the firm. The stock has fallen 9.3 percent so far this year, following a 41 percent drop in 2017.
She was also part of a consortium which spent a record $5.2 billion to buy a large part of a landmark Hong Kong skyscraper owned by local billionaire Li Ka Shing.
(Reporting by Farah Master and Donny Kwok; Editing by Gopakumar Warrier)
