Tim Cook is stepping down as chief executive of Apple, ending a nearly 15-year tenure that transformed the iPhone maker from a $350 billion company to a $4 trillion business. He will hand over the role to John Ternus, the company's head of hardware engineering, on September 1, while staying on as executive chairman.

Cook took charge in August 2011 in the most fraught of circumstances. Steve Jobs formally handed him the title just weeks before dying of pancreatic cancer, leaving Cook to lead a company many believed was inseparable from its founder.

Cook went on to nearly quadruple Apple's revenue, from $108 billion in FY2011 to more than $416 billion in FY2025 and oversaw the launch of the Apple Watch, AirPods, and the company's services business, which now generates more than $100 billion a year.

Ternus is a 25-year Apple veteran who has spent virtually his entire career at the company, rising from the product design team to lead hardware engineering in 2021. He will join Apple's board of directors when he assumes the chief executive role. In his farewell note to staff and customers, Cook described the job he is vacating as "the best job in the world."

Must read: Apple's iPhone win loyalty game again, Android sees higher switch rates
 

Here’s the full note by Apple CEO Tim Cook as he steps down as CEO

"For the past 15 years I've started just about every morning the same way. I open my email and I read notes I received the day before from Apple's users all over the world.

You share little pieces of your lives with me and tell me things you want me to know about how Apple has touched you. About the moment your mom was saved by her Apple Watch. About the perfect selfie you captured at the summit of a mountain that seemed impossible to climb. You thank me for the ways Mac has changed what you can do at work and sometimes give me a hard time because something you care about isn't working like it should.

In every one of those emails feel the beating heart of our shared humanity. I feel a sense of deepening obligation to work harder and push further. But most of all, I feel a gratitude that I cannot put into words, that somehow got to be the person on the other end of those emails, the leader of a company that ignites imaginations and enriches lives in such profound ways it defies description. What an honor and a privilege it has been.

Today we announced that I'm taking the next step in my journey at Apple. Over the coming months I will be transitioning into a new role, leaving the CEO job behind in September and becoming Apple's executive chairman. A new person will be stepping into what I know in my heart is the best job in the world. That leader is John Ternus, a brilliant engineer and thinker who has spent the past 25 years building the Apple products our users love so much, obsessed with every detail, focused on every possible way we can make something better, bolder, more beautiful, and more meaningful. He is the perfect person for the job.

John cares so much about who we are at Apple, what we do at Apple, who we reach at Apple, and he has the heart and character to lead with extraordinary integrity. I am so proud to call him Apple's next CEO. This company will reach such incredible heights under his leadership, and you will feel his impact in every bit of delight and discovery that grows out of the products and services to come. I can't wait for you to get to know him like do.

This is not goodbye. But at this moment of transition, I wanted to take the opportunity to say thank you. Not on behalf of the company, this time, though there is a wellspring of gratitude for you that overflows inside our walls. But simply on behalf of me. Tim. A person who grew up in a rural place in a different time and, for these magical moments, got to be the CEO of the greatest company in the world. Thank you for the confidence and kindness you've shown me.

Thank you for saying hi to me on the street and in our stores. Thank you for cheering alongside me when we unveiled a new product or service. Thank you, most of all, for believing in me to lead the company that has always put you at the center of our work. Every day we get up and think about what we can do to make your life a little bit better. And every day, you've made mine the best could have asked for."