CHICAGO (WBBM) — Chicago-based Groupon is experiencing some growing pains as it expands worldwide.

As WBBM Newsradio 780’s Regine Schlesinger reports, the Internet startup founded by Northwestern University graduate Andrew Mason partners with local retailers to offer daily online deals.

LISTEN: Newsradio 780’s Regine Schlesinger reports

Groupon now has 50 million subscribers in 35 countries and counting.

Last week, Groupon secured nearly $1 billion in private funding, and the Wall Street Journal reports it is about to enter the Chinese market through a partnership with one of China’s largest Internet companies.

But Groupon’s recent experience in Japan shows expansion is not always smooth.

Chief executive officer Mason has had to apologize and offer refunds to hundreds of customers who bought a deal for a traditional New Year’s meal.

Customers said the meals arrived late or were substandard. Groupon said it was misled by the restaurant it was working with, and said the popularity of Groupon in Japan has grown so quickly, companies have been caught off guard.

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