Cupertino, Calif. ? The most closely kept secret about the iPhone 5? There isn’t one — yet.

Apple unveiled a faster, more powerful version of its sleek iPhone on Tuesday and named it the 4S. It includes a futuristic, voice-activated personal assistant service and an app that will send greeting cards for $2.99 each. Sprint customers will now be able to use one.

Pre-orders will begin Friday with availability on Oct. 14.

But the new iPhone was not named the iPhone 5 or reimagined to the degree that many tech bloggers and Apple fans had hoped it would be. Wall Street seemed disappointed, too: Apple stock lost more than 5 percent before bouncing back to close down less than 1 percent.

Still, Apple stock has nearly quadrupled since the first iPhone was announced in 2007. The device has been the cornerstone of one of the most remarkable runs in technology history. Apple is now one of the world’s most richly valued companies, holding its own against oil companies and international conglomerates.

If Tuesday’s unveiling seemed like a letdown, it was because Apple didn’t do a good job of managing expectations. That’s a familiar problem for Apple, whose penchant for secrecy invites hyperbolic speculation between its product announcements. Given that it had been 16 months since the last iPhone hit the market, imaginations had even more time to run wild this time.

“This is the typical Apple scenario: People keep wanting it to do the impossible,” said Tim Bajarin, an analyst who has been following the company for decades.

Apple’s approach to the event didn’t do any favors for Tim Cook in his first major public appearance since he succeeded Steve Jobs as CEO six weeks ago. Jobs, the Apple visionary and co-founder, relinquished the reins to focus on his health problems.

As many people expected, Cook handled his presentation in a pedestrian fashion that lacked Jobs’ flair. The format and stage setting were similar to the presentations that Jobs had orchestrated so masterfully, giving Cook little opportunity to make his own mark, said Adam Hanft, a marketing consultant who runs his own firm in New York.

Even though the iPhone 4S is an improvement over its predecessor, it isn’t being perceived as a breakthrough partly because it’s not being branded as an iPhone 5 as most people had been expecting, said Prashant Malaviya, a marketing professor at Georgetown University.

Not all investors were disappointed.

Stephen Coleman, chief investment officer for Daedalus Capital and an Apple investor since 2004, calls his Apple stock “the safest investment that I own.” He said Tuesday’s upgrades were “incremental” — and praised Apple for not messing too much with a model that’s working.

“To those who say they’re underwhelmed, I’d say they’ve been fast asleep,” Coleman said. “Anyone who’s been paying attention at all would have to be dazzled by the product, and earnings.”

He cited the run-up in Apple’s stock price.

The new iPhone has an improved camera with a higher-resolution sensor. The processor is faster, which helps run smoother, more realistic action games. It’s also a “world phone,” which means that Verizon iPhones will be able to useable overseas, just as AT&T iPhones already are.