The natural-born diplomat behind this year’s biggest IPO

It’s serving him well as the chief executive of British circuit designer Arm, whose initial public offering this month is expected to be the biggest of the year. Since taking the helm of the company in 2022, he increasingly has to play statesman as well as CEO, managing relationships among competing customers and across borders.

Arm is a company many people don’t know by name, but is integral to nearly everyone’s everyday life. Arm designs parts of chips that are essential in almost all mobile phones, and it’s looking to grow in personal computers, servers and other devices. To do that, Haas, who is 61, must juggle chip-making customers who are battling each other to profit from the surge in computing demand and in artificial intelligence. Arm—and Haas—must stay neutral if they want those customers to keep it as an essential circuit supplier.

“He’s not your archetypal brash, ambitious American CEO, but there is ambition there," said Jem Davies, a former Arm senior executive who worked closely with Haas for several years. “I don’t think I’ve once seen him shout."

Haas instead prefers to keep things simple, with low drama and little distraction. His office at Arm’s U.S. headquarters in San Jose, Calif., is sparsely decorated with just a couch, some books and a table so spare that it resembles a hot desk. He likes to wear the same outfit most days to minimize time getting ready: a blue sweater and blue blazer with jeans.

Haas’s colleagues and former reports say he puts a lot of thought into the company’s strategy and then plays the role of a coach, letting his employees execute it largely without interference. A Los Angeles Lakers fan and a pickup basketball player—he stands about 6 feet, 4 inches—Haas takes inspiration from former coach Phil Jackson, who often would refrain from calling timeouts when the opposing team went on a run. His reasoning: The players know the strategy, and he trusts them.

Haas grew up in a suburb of Rochester, N.Y., where his father worked as a research scientist at Xerox. The younger Haas got a bachelor’s degree in electrical engineering in 1984 from Clarkson University, and after stints as an engineer at Texas Instruments, Xerox and NEC, moved to Silicon Valley to work in sales in the chip industry.

Haas’s first big job in chips was at graphics-processing giant Nvidia, where he spearheaded a foray into powerful graphics chips for laptops. He also worked on chips meant for mobile phones and tablets, including Microsoft’s first Surface tablet. Those chips’ incorporation of Arm’s circuit designs brought him closer to that company, where he moved in 2013.

Arm hired Haas because it wanted to get into new markets and new kinds of chips. Steeped in Silicon Valley’s business culture, Haas fit the bill, although he was unusual in another sense: He was American, and U.K.-based Arm was decidedly British.

After a couple of years in Shanghai, where he was tasked with expanding Arm’s appeal to Chinese customers, Haas relocated to London and commuted to the company’s headquarters in Cambridge.

He has since returned to California, but spends much of his time shuttling between the U.S., the U.K. and Japan, home to the company’s owner, SoftBank, which bought Arm in 2016 for $32 billion.

Haas’s road to the CEO position was paved by the failure of the chip industry’s largest-ever acquisition, Nvidia’s planned purchase of Arm from SoftBank for $40 billion in 2020. By then, he had risen up the ranks to sit just below then-CEO Simon Segars.

Nvidia envisioned Haas running its Arm business following the deal, and he began to prepare to take the mantle. The deal started to unravel at the end of 2021, however, amid concerns from regulators and some customers that Arm’s neutrality as a supplier to the chip industry could be compromised if it were owned by a chip maker.

Segars told SoftBank CEO Masayoshi Son that he was going to leave and recommended that Haas take his place, according to people familiar with the discussions. That spurred a series of in-depth conversations between Son and Haas over the following two months about how Haas would lead the company.

Haas, who lives in Silicon Valley and has two grown children, was appointed CEO in February of last year after the Nvidia deal was scrapped and SoftBank said it would pursue an IPO instead.

Already in his short tenure, Haas has had to balance his diplomatic skills with the need to defend the company from what Arm sees as threats to the growth of its business.

Last year, the company took the unusual step of suing Qualcomm, which accounts for more than 10% of its sales, over the San Diego-based mobile-phone chip company’s attempt to pay lower royalties on chips developed by a company it acquired. Qualcomm, in a response to the lawsuit, said it was shifting away from using Arm’s circuit designs because it could outcompete Arm with its own.

Other challenges loom for Haas following the IPO, which is aiming to raise at least $4.5 billion for SoftBank. The company gets around a quarter of its revenue from China, the focus of growing U.S. concern about the diversion of chip technology to the military and weapons development. There are also competitors to watch out for, most prominently an open-source chip-design standard called RISC-V, which isn’t yet a major threat but is leaping forward and getting investment from China.

Arm’s tightrope walk has also been on display in its IPO process: To avoid the appearance of favoring any customers, according to people familiar with the matter, the company offered most of its biggest buyers the same terms. Each could put in up to $100 million as a strategic investor.

Nvidia, now the world’s most valuable chip company, has backed Arm even after its acquisition fell apart last year and is planning to be a strategic investor. In a video presentation to investors as part of Arm’s IPO roadshow this week, Nvidia CEO Jensen Huang said Haas had transformed Arm, getting it into new markets and enriching its software offerings.

“Everyone in the world knows how fond I am of this company," he said.

In meetings with investors, Haas has also been playing up the chip industry’s growing geopolitical importance, recommending that prospective investors and advisers on the IPO read “Chip War," a recent book that outlines how chip-making has become critical to countries’ technological advancement.

Having an endorsement from Nvidia also helps, given that that company’s stock has more than tripled this year, sending its value above $1 trillion.

“You want Nvidia up there with you as often as you can," said a potential investor who saw the presentation. “You just mention their name and your stock takes off."

Write to Asa Fitch at asa.fitch@wsj.com and Corrie Driebusch at corrie.driebusch@dowjones.com