The S. Korean electronics giant had the world's top-selling smartphone in Q3 for the first time ever with its Galaxy S3, according to data from Strategy Analytics. But Samsung is expected to face stiff competition in Q4 from Apple (AAPL), which released a new-generation iPhone 5. The Galaxy S3 accounted for 10.7% of Q3 global smartphone shipments, with 18 mil units. The iPhone 4S was next with 9.7% of the market, with the iPhone 5 — released late in the quarter — No. 3 with 3.6%. Apple shares fell 3.6% to 537.75.