Wall Street Under Pressure as Traders Eye McDonald's

U.S. stocks began Tuesday's trading session lower as investors digested earnings beats and misses, but kept their attention firmly focused on Apple Inc.'s hotly anticipated product event later in the day.

The S&P 500 (SPX) opened 5 points, or 0.3%, at 1,996.0. The Dow Jones Industrial Average (DJI) dropped 62 points, or 0.4%, to 17,049.19 at the open. The Nasdaq Composite (RIXF) began the session down 11 points at 4,581.69.

Among economic news, small-business sentiment in August nudged up to its second-highest reading since October 2007, a trade group said Tuesday. Data on job openings for July is due at 10 a.m. Eastern. Also read: Michael Sincere on why this stock market will never go down

Stocks to watch: The iPhone maker (AAPL) will hold its product event at 10 a.m. PDT (1 p.m. Eastern) near its headquarters in Cupertino, Calif. The newest version of its flagship phone and an iWatch wearable device are among key things that could help boost shares of Apple. Also read: Tim Mullaney on why Apple exemplifies everything that's wrong about Silicon Valley.

McDonald's (MCD) said global comparable sales fell 3.7% in August and blamed "several headwinds" for the decline. The fast-food restaurant chain also warned that the problems with a supplier in China will hurt third-quarter results. Also read: The secret to a long life? Fast food

Shares of Annie's Inc.(BNNY) rose 37%, on the heels of a similar late-session rally after General Mills Inc. (GIS) offered to buy the organic foods company for $820 million in cash.

Shares of Pinnacle Foods Inc.(PF) fell 3.8% after the packaged-foods company said some shareholders tied primarily to investment firm Blackstone will sell 15 million common shares.

Barnes & Noble Inc. (BKS) shares reversed losses made immediately in the wake of the bookseller's quarterly results, and shares were up 2.7%. Same-store sales fell by more than expected, but the loss was not as large as expected. Read about more of the day's notable stock moves here.

Other markets:The yield on the 10-year Treasurys(10_YEAR) rose 3 basis points to 2.5%, its highest since the beginning of August on a closing basis. Brent crude oil prices held steady at $100 a barrel, while the dollar charted new highs against the yen (USDJPY) and the euro (EURUSD). Europe stocks posted mild losses, while Asia markets saw mostly modest gains.