Once rejected by Ken Griffin, now at 35 years old, managing $20 billion. This "short-selling fanatic" makes Wall Street love and hate him!

In 2020, young Hamza Lemssouguer received an invitation from Ken Griffin, the founder of Citadel and a hedge fund titan, to take charge of a European credit hedge fund with assets in the tens of billions. He turned it down.

Today, at 35, the Moroccan-born fund manager has gone out on his own, building Arini Capital into a credit hedge fund with assets of more than $20 billion. According to data provider Hedge Fund Research, its growth rate since inception ranks No. 1 among up-and-coming hedge fund managers.

Lemssouguer’s short bets have repeatedly paid off, earning him both admiration and fear within the industry.

His short positions in software companies such as ZipRecruiter and Unisys that he initiated in the third quarter of 2025 initially did not show results. They were then realized one after another as “the SaaS apocalypse” panic swept through the debt markets. According to people familiar with the matter, Arini’s main fund has an annual average return of roughly 15%, more than double the 7% average level of the HFR credit hedge fund index.

However, Lemssouguer’s aggressive style has also made him a target for many rivals. Competitors and bank traders have criticized his excessive reliance on leverage, which has caused performance to swing sharply—at one point, the main fund’s biggest drop in a single month reached 6%. In 2024, the fund returned only 9%, partly because he continued with short positioning even during most periods when markets were moving higher. “He has a lot of ‘black fans,’” said Rupak Ghose, an investment banker who previously provided consulting services to hedge funds and is a commentator in the financial industry.

“Look at our track record—whether the market is up or down, we can generate excess returns through strong risk management,” Lemssouguer said in an interview at a Tudor manor on the outskirts of London, a property with a history of more than 400 years. On the estate, he lives with his wife, children, and 160 rare parrots. The -n fund manager, who neither drinks nor drives and whose biggest hobby is raising parrots, is writing his own legend in the City of London in a way that feels out of place.

From Casablanca to elite schools: the growth path of an outsider

Lemssouguer was born in Casablanca, Morocco, into an ordinary family. His father worked at the port, his mother was a teacher, and there were four siblings in total.

From an early age, he was quiet and reserved. He stood out in three areas: painting, raising parrots, and mathematics. His mathematical talent opened the door to France’s top elite institution, École Polytechnique—an academy often seen as a French blend of MIT and the U.S. Military Academy at West Point.

In 2014, Lemssouguer joined Credit Suisse’s London office, taking his first step in his career.

He learned American English by repeatedly watching TV series such as Entourage and The Fresh Prince of Bel-Air.

Thanks to his strong bond trading skills, he quickly rose into Credit Suisse’s ranks of top-tier traders, and by 2016 he was managing about $100 million in proprietary capital.

Jaguar Land Rover’s bet: laying the groundwork for a contrarian trading style

2016 marked the battle that truly established Lemssouguer’s personal style.

At the time, Jaguar Land Rover’s revenue was trending up, and the market widely expected it to have its credit rating upgraded. After visiting multiple dealerships on the ground, Lemssouguer found that inventory was piling up, signaling that sales were about to slow. “I took a contrarian view,” he said.

He allocated about 10% of the portfolio’s capital to credit default swaps (CDS). Once bond investors turned bearish on the automaker, those positions would rise in value.

In 2017, Jaguar Land Rover’s sales data indeed deteriorated, and the trade generated about five times the return for Credit Suisse. After that, Lemssouguer formed a fixed trading pattern: dig deep into the data, form high-confidence judgments, and push positions to their limits.

Whenever he landed a major win, he would play music from his favorite rapper, The Notorious B.I.G., on the trading floor.

A former colleague recalled: “When I heard how Hamza performed in his first year, I thought, ‘Sure—anyone can hit luck once.’ Later, when he kept succeeding in his second year, I thought, ‘Next year he’ll definitely lose everything’—but he never lost.”

Rise to fame in the COVID episode, then reject Griffin’s invitation

In early 2020, as the COVID pandemic spread, Lemssouguer launched a short-selling offensive targeting companies with tight cash flows, totaling roughly $1 billion, including Europcar Mobility Group, an auto rental company.

In Q1 2020, this strategy netted about $220 million in profit.

And it was in that same year that Citadel extended an olive branch to him, inviting him to run a European credit fund.

Lemssouguer initially agreed, then changed his mind—Credit Suisse kept him on the condition that it would help him set up an independent fund and take his existing trading team with him.

However, right on the eve of when the plan was set to begin in early 2021, Credit Suisse’s hedge fund business abruptly collapsed. He was forced to find new backers and ultimately secured support from the large hedge fund Squarepoint Capital.

Arini arrives: assets under management surge by more than 15x in two years

In early 2022, Arini Capital was officially launched with $1.3 billion, focusing on highly leveraged companies—making loans to some firms and buying or shorting bonds of others, often with heavy concentrations.

But the start was not smooth: when the Russia-Ukraine war broke out, global interest rates surged, European corporate bond prices fell sharply across the board, and the fund lost 15% from March to September that year. Lemssouguer later admitted that the biggest mistake at the outset was not having a dedicated risk-hedging trader on the team.

Even so, Arini finished the year with a positive return of 4%.

After that, Lemssouguer brought in trader Ardacan Celebi from Deutsche Bank—also a graduate of a French mathematics elite school. Celebi built what Arini internally calls a “risk mitigation engine,” combining tools such as derivatives, bonds, and ETFs to absorb market shocks, enabling the fund to maintain an aggressive positioning even in choppy markets.

“Maximum drawdown is what can force you out,” Celebi said.

So far, the Arini team works closely together with analysts and traders from multiple countries, including Afghanistan, Turkey, and Ukraine.

Once the main fund’s scale reached $4 billion, it closed to outside investors. The company is now aggressively expanding collateralized loan obligations (CLOs) and private credit business—these fee rates are lower than those of hedge funds, but the scale potential is bigger. About 60% of its fundraising comes from North America.

Model controversy: can centralized collaboration stand up to market pressure?

In terms of operating structure, Arini is starkly different from multi-strategy platforms such as Citadel.

On the latter, multiple independent teams under one roof compete with each other and operate separately. At Arini, however, all funds share the same research team of 20 industry analysts, using unified information and coordinated analysis. Lemssouguer believes this model allows the company to capture investment opportunities faster.

But critics point to potential hazards: the portfolios of different funds may therefore be highly correlated, and if markets undergo a sudden shift, risks could concentrate and erupt. In addition, Arini’s “risk mitigation engine” has yet to face the real test of a prolonged market downturn.

Facing criticism from all directions, Lemssouguer still maintains his consistent contrarian approach.

“Young, and as an outsider and non-traditional player, means I won’t become arrogant about the market,” he said.

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