Mr Lim Hock Chee and his wife used to sell chilled pork at a rented stall in a grocery store.

Now, after more than 35 years, his family operates 61 supermarkets across Singapore and has joined the ranks of billionaires.

Shares of their Singapore-listed Sheng Siong Group rose to a record on Wednesday as supermarkets have become the preferred place to shop after the Government imposed a partial lockdown to contain the coronavirus pandemic. The stock has rallied more than 30 per cent since a March 19 closing low.

The family's combined fortune, based on their 57 per cent stake in the supermarket chain held mainly by Mr Lim and his two brothers, has surged to US$1.1 billion (S$1.57 billion), according to the Bloomberg Billionaires Index.

That would have been inconceivable when Mr Lim started the pork stall to help alleviate a supply glut at his father's pig farm. The brothers took over the supermarket where the stall was located and turned it into the first Sheng Siong store in 1985, and today is planning a foray into Singapore's digital banking scene.

The founders declined to comment on their wealth, according to a Sheng Siong spokesman. The brothers and their family were thrust into the media spotlight in 2014, when their mother was kidnapped. She was released unharmed after Mr Lim paid a ransom, and the kidnapper was later sentenced to life imprisonment.

Regulatory filings show Mr Lim bought more shares in the company last month through an account jointly held with his wife. He may have learnt a thing or two from previous outbreaks.

"When people stayed away from restaurants during Sars (severe acute respiratory syndrome), we enjoyed brisk business because more people started buying food to cook at home," he said in a 2008 interview with The Straits Times.

Grocery purchases are likely to remain robust even if social distancing measures and panic buying abate, according to Ms Juliana Cai, an analyst at RHB Securities Singapore.

"Employees are likely to be encouraged to continue working from home to prevent another wave of the viral contagion," she wrote in a note, maintaining Sheng Siong as her top pick among consumer-focused stocks.

The Lims are not the only ones benefiting from a surge in grocery spending.

Amazon.com, which owns Whole Foods Market, surged to another record on Wednesday, lifting the fortune of founder Jeff Bezos to US$139.8 billion. Alice, Jim and Rob Walton, members of the world's richest family, now have a combined net worth of US$168.5 billion as shares of their Walmart Inc climbed 8.4 per cent this year.

Mr Radhakishan Damani, who controls Avenue Supermarts in India, now has a net worth of US$10.7 billion, an increase of about 10 per cent since the start of the year.

DBS Bank analysts said they expect Sheng Siong to boost its earnings over the next two years, citing social distancing and stimulus measures, as well as cost cuts. The company posted net income of $75.8 million on revenue of $991.3 million last year.

"Sheng Siong's target customers (comprise) not so much of millennials who are open to online grocery shopping," DBS analysts Alfie Yeo and Andy Sim wrote in a note to clients on Wednesday.

The grocer, with its "decent" store network and logistics chain, eventually could be a takeover target for online players, they wrote.

The brothers are already considering branching out from its core business. Sheng Siong Holdings, a private entity owned by the Lims, is part of a consortium led by local gaming company Razer that has applied for a digital banking licence.

In an interview last year with tax and consulting firm RSM Singapore, Mr Lim said people should embrace change because "the world never stops turning".

BLOOMBERG