There is no Aldi stock symbol or price quote because it is a private family owned business that has never been released in an initial public offering. Aldi’s company is based in Germany and owned by the Albrecht family.
Aldi is the brand of two German family-owned discount supermarket chains with more than 10,000 stores in 20 countries and an estimated combined value of €50 billion that has its equity 100% owned by the Albrecht family. Aldi was founded by brothers Karl and Theo Albrecht in 1946 in Germany when they took over operations of their mother’s store in Essen. The grocery chain was divided into two different groups in 1960, and became Aldi Nord, headquartered in Essen, and Aldi Süd, headquartered in Mülheim. 
Aldi’s U.S. operations are headquartered in Batavia, Illinois, its division now has more than 2,000 stores in 36 states and employs over 25,000 people and has been steadily growing since opening its first US store in Iowa in 1976. Aldi has the third most stores of any grocery chain in the U.S., however their stores are much smaller than the bigger grocery chains.
The company that most resembles their operation and market niche is likely Dollar General in size, targeted customer base, and operational structure. Dollar General’s ticker symbol is $DG for investors that want exposure to a similar business model as Aldi.
Aldi is a very large multinational corporation that is able to operate by reinvesting its own capital for growth so has never needed an IPO to raise investor capital, this gives the owners freedom to operate with no need to meet Wall Street expectations with earnings and growth. If Aldi ever went public it would likely have its stock listed on a European exchange and trade on a U.S. exchange as an American Depository Receipt (ADR).