For the second time in as many years, Apple (NASDAQ:AAPL) CEO Steve Jobs has handed the keys to his $320 billion tech darling to Tim Cook.

Cook, 50, is widely respected in the industry and as Apple’s chief operating officer has been Jobs’s trusted No. 2 for years. He also took the reins at Apple in April 2009 when Jobs took a medical leave of absence to receive a liver transplant after being diagnosed with pancreatic cancer.

Apple’s stock is already tumbling in Frankfurt (U.S. markets were closed Monday in observance of Martin Luther King Day) as investors ponder life without Jobs, the face and brains of the highly-successful tech company.

From an operating standpoint, Cook is as good as it gets as a No. 2. He’s been with Apple for more than a decade -- he joined in March 1998 -- and has also worked at Compaq, Intelligent Electronics and IBM (NYSE:IBM), where he led its North American manufacturing and distribution functions for PCs.

“He’s an incredibly good No. 2,” said Rob Enderle, principal analyst at the Enderle Group.

At the same time, “He doesn’t have the magic or charisma Steve Jobs does. He certainly can’t replace Steve Jobs. Right now Steve Jobs is largely irreplaceable,” Enderle said, comparing him to Walt Disney, the founder of Disney (NYSE:DIS).

Hailing from Alabama, Cook attended Auburn University and went on to receive his MBA from Duke University, where he was a Fuqua Scholar, in 1988.

He’s more of a big-picture guy, rather than the hands-on, micromanager that is Jobs. Enderle called Cook a “good operational manager” and said he is “very well known and well regarded inside” Apple.

After being recruited by Jobs himself, Cook revamped Apple’s supply chains to ensure the company became more efficient and stock levels were at a minimum.

But he’s not the PR-savvy showman like Jobs, who seems to bask in the glory of the attention his product announcements always have. According to the U.K.’s Guardian, Cook hasn’t even unveiled a new product in front of an audience.

“With Tim cook in place, Apple is not as valuable a company. You are talking about a company that is valued significantly less,” said Enderle.

The problem for investors is that Apple hasn’t given a timetable for Jobs’s return. He will stay on as CEO, but Cook will be in charge of the day-to-day operations. The company could give clues about the situation during its conference call with analysts and reporters after releasing its quarterly results on Tuesday after the bell.

"Apple is very good at spinning bad news,” said Enderle. Then again, "without Jobs they won’t be as effective in spinning this, so we’ll see.”