Wingstop Inc. shares dropped in the extended session Thursday after the chicken-wing franchise’s outlook fell short of Wall Street estimates. Wingstop shares fell 9% after hours. For the year, Wingstop estimates earnings of 75 cents a share, while analysts surveyed by FactSet expect earnings of 83 cents a share. The company reported fourth-quarter net income of $10.5 million, or 36 cents a share, compared with $4.3 million, or 15 cents a share, in the year-ago period. Adjusted earnings were 17 cents a share. Revenue rose to $28.3 million from $24.6 million in the year-ago period. Analysts had estimated 16 cents a share on revenue of $27.5 million.