With Larry Ellison and Steve Ballmer having stepped down as CEO, there are few leaders of the world’s biggest tech and IT companies that can claim the kind of staying power. CBR rounded up some of the longest-serving tech CEOs.

1. Ren Zhengfei – Huawei

Years as CEO: 28

Ren Zhengfei founded the Chinese electronics and networking giant back in 1987. Huawei started out selling telephone exchange equipment from Hong Kong but is now one of the world’s largest networking companies with a line of low-cost consumer phones. Ren is famously reclusive, but spoke recently at the Davos conference to outline his company’s ambitions for the future and deny US spying allegations.

2. Jeff Bezos – Amazon

Years as CEO: 21

Bezos’s tenure as CEO of Amazon stretches back to a time when Amazon was a humble online bookseller, so his inclusion on this list is arguably contentious. During his leadership Amazon has transitioned to the world’s leading provider of Cloud in Amazon Web Services. It has also made forays into the electronics market with the Kindle. Bezos owns the Washington Post and according to Forbes currently has a net worth of $38.4 billion.

3. John Chambers – Cisco

Years as CEO: 20

Although it will not go on much longer, Chambers has had the longest uninterrupted spell as CEO of a US tech company. Chambers hands the company over to Chuck Robbins in July, claiming to have "no regrets" about stepping down at the "most exciting time" in the company’s history. He has led the company through the dawn of the internet age, the dot-com bubble and the Great Recession.

4. Michael Dell – Dell

Years as CEO: 20

Despite a three-year hiatus between 2004 and 2007, Dell’s impressive stint at his eponymous company stretches back to 1992. The company began in the early 1980s as ‘PCs Limited’, which sold upgraded IT hardware. Dell is now Chairman of the Board and in March 2015 Forbes puts his net worth at $18.7 billion. In 2013 he took the company off the stock exchange in a leveraged buy-out alongside Silver Lake Partners.

5. Joseph M. Tucci – EMC

Years as CEO: 14

Tucci joined EMC in 2000 as president and chief operating officer, taking the CEO role in 2001. He became Chairman in 2006 and just to make it official, President in 2014. During his tenure, Tucci has moved EMC’s model from focusing on high-end storage platforms to building a comprehensive portfolio, spearheaded an aggressive strategic acquisition strategy, and extended the company’s focus from large enterprises to commercial and small-medium businesses.