Shares of the Dallas company were falling 16.4% to $138.71 at last check.
Wingstop reported a net loss of $6.4 million, or 21 cents per share, compared with net income of $3 million, or 10 cents per share, a year ago. Adjusted earnings came to 18 cents per share, missing the FactSet consensus for 23 cents.
Revenue totaled $63.3 million, up 19% from $53.2 million a year ago. FactSet's forecast called for revenue of $64.1 million.
The company said income was affected by $13.7 million of expenses associated with the refinancing of debt and payment of a special dividend.
Domestic same-store sales rose 18.2% beating the FactSet consensus for 17% growth. Digital sales increased to 62.5% of sales, compared with 38.2% in the year ago quarter.
For the quarter, system-wide sales increased 26.5% to $502.5 million, and the company reported 59 net new openings.
Domestic restaurant average unit volume (AUV) increased to about $1.49 million, compared with $1.25 million in the prior fiscal fourth quarter.
The company reaffirmed its three-to-five year outlook of mid-single digit domestic same store sales growth.
As of Dec. 26, Wingstop had 1,538 restaurants system-wide, of which 1,327 were franchised restaurants in the U.S., 32 were company-owned, and 179 were franchised restaurants in international markets.
The board also declared a quarterly dividend of 14 cents per share.
"2020 further proved the resiliency of our model and we're truly humbled by our results," Charlie Morrison, chairman and CEO, said in a statement. "We remain focused on our strategic long-term growth drivers and driving shareholder value as we work toward our vision of becoming a top 10 global restaurant brand."