By early afternoon, the stock had crumbled 9.7% to $20.22. Trading volume of 2.3 million was nearly six times its three-month daily average.
The sandwich chain recorded a loss of $3.7 million in the three months to December, compared to profit of $18.5 million in the year-ago quarter.
Adjusted net income of 6 cents a share beat expectations of 4 cents a share, according to analysts surveyed by Thomson Reuters.
Quarterly revenue of $74.76 million fell short of consensus of $76.09 million. Company-owned same-store sales rose a weak 0.7% over the quarter, namely due to lower store traffic resulting from harsh wintry weather. The year-ago quarter's calendar also had an additional operating week.
"We delivered adjusted net income of $1.9 million or $0.06 per diluted share for the quarter, which represents roughly 35% growth, after eliminating the 53rd week impact from 2012 and neutralizing the tax rate difference," CEO Aylwin Lewis said in a statement.
"There is no question the external environment was disruptive during the quarter; however, we remained resilient and delivered top and bottom line growth in our comparable shops, opened thirteen new shops and managed overhead diligently to deliver solid returns for the quarter."
Over 2014, management expects adjusted net income to grow between 25% and 35%, with low single-digit comparable-store sales growth.