Red Robin Gourmet Burgers Inc. shares plummeted 15% in the extended session Tuesday after the company missed earnings expectations. The casual dining company's stock closed down 4.5% to $57.95 during regular trading. The company reported fiscal first-quarter net income of $4.4 million, or 34 cents a share, compared with $11.6 million, or 89 cents a share, in the year-ago period. Adjusted earnings were 69 cents a share. Revenue rose to $421.5 million from $420.6 million in the year-ago period. Analysts surveyed by FactSet had estimated adjusted earnings of 76 cents a share on revenue of $427 million. For the fiscal second quarter, analysts model adjusted earnings of 75 cents on sales of $326 million. The company said it expects earnings of 55 cents to 75 cents a share in the second quarter. Prior to Tuesday's after-hours move, Red Robin stock gained 2.8% this year, with the S&P 500 index rising 2.2%.