India, Sept. 1 -- John Ternus officially took over as Apple CEO on Tuesday, replacing Tim Cook after nearly 15 years at the top. Cook became CEO on August 24, 2011, taking over from Apple co-founder Steve Jobs. Ternus is now taking charge of a company that has grown into one of the world's biggest and most valuable businesses under Cook.

Apple shares have risen about 2,275% since Cook became CEO in August 2011. When Cook took over, Apple had a market value of less than $350 billion. Today, Apple is valued at around $4.6 trillion, according to Bloomberg. The company has also expanded beyond the iPhone and Mac into products such as the Apple Watch and AirPods, as well as financial services.

Apple's stock gained a massive 2,736% on a total...