* Sees slight improvement in restaurant margins for FY 2011
* Shares fall 5 pct in extended trade
Sept 14 (Reuters) - Drive-in restaurant chain Sonic Corp (SONC.O) reported a 6.4 percent decline in fourth-quarter same-store sales, sending its shares down 5 percent after the bell.
Sonic, whose sales have been hit due to the high unemployment rates among its core demographics, said same-store sales in its drive-ins were down 6.1 percent for the quarter.
For fiscal 2011, the company expects slight improvement in restaurant-level margins as a result of labor efficiencies, it said in a statement.
Sonic expects improvement in same-store sales in 2011, as its sales initiatives boost traffic, the company said.
Weaker spending by youth, who account for a large number of fast-food customers, has hurt sales at fast food chains including Sonic.
Shares of the company, which have lost about 18 percent of its value since it reported its third-quarter results, closed at $7.65 Tuesday on Nasdaq.
Reporting by NR Sethuraman in Bangalore; Editing by Prem Udayabhanu