Karl Albrecht, the reclusive German businessman who became one the world’s wealthiest people after co-founding the Aldi discount supermarket chain in the 1960s, died July 16 in Essen, Germany. He was 94.

The Frankfurter Allgemeine Zeitung reported the death but did not disclose the cause.

Mr. Albrecht was the second-richest person in Germany and the 35th-wealthiest in the world, with an estimated fortune of $20.9 billion, according to the Bloomberg Billionaires Index. With his brother, Theo, he built a business that ranked as the world’s 11th-biggest retailer in 2013, according to London-based research company Planet Retail.

The Albrecht brothers split the Essen-based chain into separate companies — Aldi Süd and Aldi Nord — in 1962, following a feud over whether to sell cigarettes in the stores.

Karl, who didn’t give interviews and withdrew entirely from public life early in his career, took up management of Aldi Süd, which has outlets in southern Germany and the United States, Britain, Australia and Eastern Europe.

Karl Albrecht, co-founder of global discount supermarket chain Aldi. (Aldi Sued/European Pressphoto Agency)

Aldi Süd operates more than 4,860 stores, according to its Web site. Its 2013 revenue was about $51 billion, Planet Retail data show.

The brothers pioneered a low-cost business strategy that focused on a limited assortment of goods, pared-down supply expenses and a minimal level of advertising. The result was a shopping experience that lacked the refinement of brightly lit supermarket chains. But consumers often paid less than they would have elsewhere.

Karl Hans Albrecht was born Feb. 20, 1920, in Essen. His father was a miner and baker, and his mother ran a grocery store. He served in the German army during World War II and was wounded on the Russian front.

The Albrecht brothers took over their mother’s store in Essen in 1946 and within seven years developed it into a 30-outlet network of discount supermarkets that served the region. The first Aldi supermarket outside Germany opened in Austria in 1967 and the first U.S. store in 1976.

In 1971, Theo was kidnapped by amateur con men, who demanded 7 million deutsche marks from the family. Karl successfully negotiated his brother’s release, and the kidnappers — a convicted burglar and his attorney — were later arrested.

Karl stepped down as Aldi Süd chief executive officer in 1994 and as chairman in 2002.

Theo Albrecht, who also owned the Trader Joe’s specialty grocery chain in the United States, died in 2010 at 88.

Karl Albrecht established the Elisen Foundation to support cultural causes, and his Oertel trust, which controlled a portion of Aldi Süd, also donates to medical research. His hobbies included golf, raising orchids and collecting antique typewriters.

With his wife, Maria, Mr. Albrecht had a daughter, Beate, and a son, Karl Jr., all of whom survive him.

— Bloomberg News