Tim Cook is out as Apple CEO. He gave a 15-year masterclass in succeeding a legend.

Tim Cook's final day as Apple CEO was on Monday, August 30.

Fabrice COFFRINI / AFP via Getty Images Tim Cook's transformational tenure as Apple CEO came to an end this week.

He succeeded as Steve Jobs' successor by combining his strengths and judgment with Jobs' values.

After 15 years in the role, Cook has made way for John Ternus.

Tim Cook has stepped down as Apple CEO, marking the end of one of the greatest tenures in business history.

Cook took on the daunting task of succeeding Steve Jobs, just weeks before his premature death in October 2011.

Vanishingly few people would have dared follow Jobs , Apple's iconic cofounder who reshaped how the world works with revolutionary devices such as the iPod and iPhone.

Yet Cook pulled off what few thought possible: taking Apple to the next level .

During his 15 years in charge, Apple roughly quadrupled its annual net sales and net income to over $400 billion and $100 billion, respectively, catapulting its market capitalization from around $350 billion to $4.6 trillion.

Adjusted for stock splits, Apple's stock price rose by nearly 2,300% during his tenure, from about $13 to $317 at the close of Cook's last day as CEO on Monday.

Now that Cook has made way for his own successor — Apple's hardware chief John Ternus — there are clear lessons to be learned from his success in following a legendary CEO.

1.

Keep what works Cook safeguarded the core values that Jobs instilled at Apple.

He told "CBS Sunday Morning" earlier this year that he protected principles such as focus , collaboration, obsession with the user experience, "insanely great" execution, and creating "magic" by owning the intersection of hardware, software, and services.