Groupon ( GRPN ) shares tumbled in premarket trading Wednesday, a day after the company reported an unexpected loss.

The e-commerce platform reported a net loss of $9.4 million for the second quarter, smaller than the $12 million loss Groupon reported a year ago. However, analysts had expected the company to start consistently producing profitable quarters starting with a projected $2 million profit in Q2, according to consensus estimates compiled by Visible Alpha.

Revenue of $124.6 million beat estimates but fell 3% year-over-year.

Road Ahead Has ‘Numerous Challenges’

“While our transformation still faces numerous challenges, including site reliability, I am confident we can restart the engines of growth and realize our mission to become the ultimate destination for local experiences and services,” Groupon Chief Executive Officer (CEO ) Dusan Senkypl said.

Senkypl said in Tuesday’s earnings call that the company has had site reliability issues multiple times so far this year, including this month due to a “cloud migration project.”

Groupon shares were down 17% to $12.99 two hours before the opening bell. An opening price below $13 would put Groupon shares back around where they started the year.