US burger restaurant chain Shake Shack has seen a fall in shares by as much as 8%, after confirming a net loss of $1.4 million (£936,000) for the period, compared to $997,000 a year earlier. The earnings report was Shake Shack's first as a publicly listed company.

The firm said the loss was due to a $1.1 million tax charge related to its initial share offering, and noted that same-store sales rose 7.2% during the period ending 31 December 2014, beating analyst expectations.

Shake Shack's chief executive, Randy Garutti, said: "We are pleased with the strength of our fourth-quarter results and excited to begin our journey as a public company."

"We are witnessing a seismic shift in people's understanding and expectations of food and, for the last decade, Shake Shack has helped lead the change in consumer behaviour through our fine casual approach," he added.