By Nell Mackenzie and Sinead Cruise

LONDON There are few jobs Robyn Grew has not mastered at the $145 billion hedge fund Man Group, where money keeps rolling in to a fast-growing business she helped to transform.

Grew, named incoming CEO on Thursday, has held executive positions in compliance, trading, legal and operations over 14 years, as Man has evolved from a disparate group of siloed businesses to a big, technology-driven investment manager.

As she becomes one of the most powerful women in fund management, Grew must apply her insights to a host of challenges from mounting competition, expanding regulations and heightening geopolitical tension.

"There aren't many people who have covered as broad a range of activities as she has. She knows the business inside out," said Jonathan Sorrell, president at New York-based $10 billion Capstone, who worked alongside Grew at Man and previously held her current job as president.

"She'll be comfortable making the big calls that are required," he told Reuters.

The London-listed firm will be led by two women for the first time in its 240-year history by the end of 2023, after long-standing CEO Luke Ellis retires in September and Anne Wade replaces veteran banker John Cryan as chair.

Grew showed her mettle alongside CEO Luke Ellis and predecessor Emmanuel (Manny) Roman in executing a decade of repositioning and growth for the hedge fund, said Dev Sanyal, CEO of Varo Energy, and former Man non-executive director.

That achievement, he said, might mean only tweaks are needed.

"There's a nimble agility to the company today and it's not in need of massive change. Robyn has been an ally of Manny and Luke in creating the success of the company," said Sanyal.

Roman doubled the size of Man's executive committee when he took over from Peter Clarke as CEO in 2013. That committee oversaw a revival plan to recoup falling assets and reverse poor stock performance.

Sanyal credited Grew, a member of the leadership team at the time, for subsequently championing the hedge fund's solutions business, where clients were given opportunities to select investment bets and strategies better suited to their needs rather than investing in a one-size-fits-all portfolio.

The business helped Man turn the tide on years of years of erratic net inflows. Man Group now has over 60% of its assets working this way.

Grew also improved the firm's compliance, he said. "She has never taken a tick-the-box approach. She helped people truly understand what was needed. She took the time and actually helped people become better at their jobs," he said.

Under her guidance, Man executed a further corporate overhaul in 2019, which simplified the company's regulatory capital requirements and laid the foundations for bigger investment in product innovation. She spearheaded its diversity programme and works with several industry-level initiatives.

"Ultimately, she is someone you can always count on," said Sorrell.

Currently based in New York, Grew will relocate to London by the time she takes up her role but Man has flagged that she will continue to spend substantial time in the U.S., where it is focused on building its brand to compete against its rivals there.

While some might view the transatlantic leadership plan as a slight on London's hedge fund scene, others were more optimistic about the role Grew could play in advocating for UK funds in the U.S., where billionaire managers like Bridgewater founder Ray Dalio and Pershing Square boss Bill Ackman are household names.

One senior hedge fund source told Reuters her appointment might help the UK asset management industry become more visible to U.S. investors, looking to Europe and Asia much more as the dollar weakens.

"Any CEO of Man Group will spend a decent amount of their time in the States as it is where the majority of the client capital comes from and where a lot of the money is invested from," said Capstone's Sorrell.

Grew lives in New York with her wife, son and "energetic cockapoo," it says on Man's website. But she grew up in Essex, to the east of the UK capital, where she attended a grammar school before reading business law at Coventry University.

Moving to finance, Grew held senior compliance roles at Lehman Brothers, Barclays Capital and later worked at LIFFE, the futures exchange subsequently named ICE Futures Europe.

She joined Man GLG in 2009 as its chief compliance officer but moved on to work as global head of legal and compliance, chief operating officer, general counsel, group COO and head of ESG and currently works as its president. She'll take up the role of CEO on September 1.

"Well, what a day," said Grew in a LinkedIn video post.

(Reporting by Nell Mackenzie and Sinead Cruise; editing by Elisa Martinuzzi and David Gregorio)