NEW YORK ( TheStreet) -- Sonic Corporation (Nasdaq: SONC) is trading at unusually high volume Thursday with 2.8 million shares changing hands. It is currently at four times its average daily volume and trading up 46 cents (+5.5%) at $8.77 as of 3:05 p.m. ET. Sonic has a market cap of $483.7 million and is part of the services sector and leisure industry. Shares are up 18.6% year to date as of the close of trading on Wednesday. Sonic Corp. operates and franchises a chain of quick-service drive-in restaurants in the United States. As of October 03, 2011, the company operated and franchised approximately 3,500 drive-ins. It also leases signs and real estate. The company has a P/E ratio of 33.2, equal to the average leisure industry P/E ratio and above the S&P 500 P/E ratio of 17.7. TheStreet Ratings rates Sonic as a hold. The company's strengths can be seen in multiple areas, such as its revenue growth and good cash flow from operations. However, as a counter to these strengths, we also find weaknesses including deteriorating net income, poor profit margins and generally poor debt management. You can view the full Sonic Ratings Report. See all heavy volume stocks in our stocks moving on unusual volume list or get investment ideas from our investment research center.