Earnings Buzz: Apple Inc (AAPL), Twitter Inc (TWTR), LinkedIn Corp (LNKD), Pfizer Inc (PFE)

As Apple Inc. releases quarterly results after the closing bell on Monday, the earnings season gets into full swing this week. Social media company Twitter Inc. and drugmaker Pfizer Inc. report results Tuesday, followed by professional networking site LinkedIn Corp. and oil and gas giant Exxon Mobil Corporation on Thursday.