Apple's new hardware will build on software announced earlier this year at the Apple Worldwide Developers Conference, where the company promised to create an augmented reality platform that would let app developers create interactive services for iPhone users.
Creating an ecosystem that keeps users engaged could be key in satisfying Wall Street's lofty expectations and maintaining Apple's status as the most highly valued public company in the world. If Apple successfully impresses consumers with its new devices, it could be on track to become a trillion-dollar company.
Analysts have largely brushed off Apple's quarterly financials this year, looking toward the holiday season and the new crop of devices. Apple is expected to sell a record 85 million iPhones in the quarter ending in December, according to FactSet. That could include over 300 million upgrades, according to former Apple analyst turned venture capitalist Gene Munster.
Apple has contributed to the latest buzz by lifting its revenue guidance. The company said in August that it expects fiscal fourth-quarter revenue of $49 billion to $52 billion, topping estimates at the time.
Apple shares have jumped 53 percent in the past year, more than triple the gains for the S&P 500.
Over 37.3 million Apple shares traded by 2:10 p.m. ET on Tuesday, well above the stock's 30-day average volume of 27.7 million shares. Shares whipsawed in afternoon trade, rising amid announcements like the Apple Watch Series 3, but dipping into the red by the end of Apple's event.
— CNBC's Arjun Kharpal, Gina Francolla, Todd Haselton, Megan Hawkins and Josh Lipton contributed to this report.