Groupon's beleaguered stock hit another low on Tuesday as investors continued to question the sustainability of its business.

Groupon’s beleaguered stock hit another low on Tuesday as investors continued to question the sustainability of its business.

Barclays downgraded it to “Underweight” citing slowing growth.

Shares of the online deals company fell 11 cents, or 2.4 percent, to close at $4.54. Earlier, the stock hit $4.34, its lowest level since going public. Groupon Inc. priced at $20 when it went public in November.

Groupon’s long-term goal is to transform local e-commerce the way Amazon transformed online retail. But the Chicago company has a long way to go, if it’s to get there at all.

Mark May of Barclays says slowing customer growth could mean higher marketing costs. He also cites the growth in sales of physical goods as opposed to local deals as a risk to profit margins.