Groupon (GRPN) - Get Report shares dropped Tuesday after analysts at Goldman Sachs slapped a sell rating on the stock of the coupon company and cut its price target.

At last check the stock was off nearly 9% to $2.40 after Goldman cut its rating from neutral, citing weakness across several key metrics of Groupon's business.

Goldman in particular cited seven quarters of declines in the number of customers, weakness in the North American operations, and a dimmer forecast on revenue, billings and gross profit for 2020 and 2021.

The firm slashed its price target for the Chicago company to $2.40 a share from $3.20.

While Groupon has invested heavily to improve the customer experience with a mobile app, card-linked offers, online booking and an overall expansion in offers, Goldman analysts wrote they are concerned about the decline in customers, which appears to be accelerating.

Groupon has lost 2.9 million customers through the first nine months of 2019, Goldman said.

The drop is the "worst on record." While a good long-term investment, the money spent on upgrading its core business has "yet to prove effective as evidenced by 2019 to-date results," Goldman noted.

Groupon's international business, until now a bright spot, is also showing signs of trouble, in part due to the fallout from Brexit in the United Kingdom, the report says. 

The international customer base fell in the first and third quarters of 2019.

"Against the backdrop of continued macroeconomic challenges (e.g., Brexit), we expect international challenges to persist," the Goldman analysts noted.

For the first nine months of 2019, Groupon's net loss widened to 17 cents a share from 10 cents in the year-earlier period. Revenue declined 13% to $1.61 billion.