Once rejected Ken Griffin, now at 35 manages $20 billion—this “short-selling fanatic” is both loved and hated by Wall Street!

2020, the young Hamza Lemssouguer received an invitation from Ken Griffin, founder of hedge fund giant Citadel, to manage a multi-billion dollar European credit fund. He turned it down. Now, this 35-year-old Moroccan fund manager has established his own firm, Arini Capital, building it into a credit hedge fund managing over $20 billion in assets. According to data provider Hedge Fund Research, Arini’s growth rate since its inception ranks first among emerging hedge fund managers. Lemssouguer’s short-selling bets have repeatedly seized opportunities, earning both respect and fear in the industry. His short positions in software companies like ZipRecruiter and Unisys, initiated in the third quarter of 2025, initially showed no results. Later, as the “SaaS doomsday” panic swept the debt market, they paid off successively. According to insiders, Arini’s main fund has an average annual return of about 15%, more than twice the HFR credit hedge fund index average of 7%. However, Lemssouguer’s aggressive style has also made him many enemies. Competitors and bank traders criticize his excessive reliance on leverage, resulting in highly volatile performance—the main fund once dropped as much as 6% in a single month, and only returned 9% in 2024, partly because he persisted with short bets even during most market rallies. “He has a lot of ‘haters’,” said Rupak Ghose, an investment banker and finance industry commentator who used to advise hedge funds. “Look at our track record—regardless of market ups and downs, we achieve excess returns through strong risk management,” Lemssouguer said in an interview at his 400-year-old Tudor manor outside London. There, he lives with his wife, children, and 160 rare parrots. A fund manager who neither drinks nor drives, whose greatest hobby is raising parrots, is writing his own legend in the London financial district in a rather unconventional way. From Casablanca to Elite Schools: The Growth Trajectory of an Outlier Lemssouguer was born in Casablanca, Morocco, to an ordinary family. His father worked at the port, his mother was a teacher, and he had three siblings. He was quiet from an early age and excelled in three things: painting, raising parrots, and mathematics. His talent in mathematics opened the doors to France’s elite École Polytechnique—a school seen as the French version of MIT and West Point. In 2014, Lemssouguer joined Credit Suisse’s London office, taking his first step in his career. He mastered American English by repeatedly watching US TV shows like “Entourage” and “The Fresh Prince of Bel-Air.” Thanks to his outstanding bond trading ability, he quickly became one of Credit Suisse’s top traders, managing about $100 million in proprietary funds by 2016. Jaguar Land Rover Bet: Establishing a Contrarian Trading Style 2016 brought the battle that truly established Lemssouguer’s personal method. At that time, Jaguar Land Rover's revenue was rising, and the market was generally expecting its credit rating to be upgraded. After visiting several dealerships, Lemssouguer discovered that inventory was piling up, signaling slowing sales. “I took a contrarian view,” he said. He allocated about 10% of his portfolio to credit default swaps (CDS); if bond investors turned bearish on the carmaker, these positions would appreciate. In 2017, Jaguar Land Rover’s sales did decline, earning Credit Suisse a roughly fivefold return. After this, Lemssouguer formed a fixed trading model: deep data analysis, high-confidence judgement, and making concentrated bets. With each major win, he celebrated at the trading desk by playing music from his favorite rap artist, The Notorious B.I.G. A former colleague recalled, “When I heard about Hamza’s performance in his first year, I thought, ‘Whatever, anyone can get lucky once.’ Then when he succeeded again the second year, I thought, ‘He’s surely going to lose it all next year’—but he never did.” Famous from the Pandemic, Then Declining Griffin’s Offer In early 2020, as the COVID outbreak spread, Lemssouguer launched short attacks totaling about $1 billion against companies with tight cash flows, including car rental firm Europcar Mobility Group. In the first quarter of 2020, this strategy netted around $220 million in profits. That same year, Citadel extended an olive branch, inviting him to run a European credit fund. Lemssouguer initially accepted but later backed out—Credit Suisse retained him with promises to help him build a standalone fund and bring his original trading team. However, just before his planned launch in early 2021, Credit Suisse’s hedge fund business abruptly collapsed. He was forced to seek new backers and eventually got support from major hedge fund Squarepoint Capital. Arini Emerges: Asset Scale Surges More Than 15 Times in Two Years In early 2022, Arini Capital launched officially with $1.3 billion in assets, focusing on highly indebted companies: lending to some, buying or shorting others’ bonds, often with heavy concentrations. The start was bumpy—the Russia-Ukraine war broke out, global interest rates soared, European corporate bond prices fell, and the fund lost 15% from March to September that year. Lemssouguer later admitted not having a dedicated risk hedge trader at launch was the biggest mistake. Despite this, Arini ended the year with a 4% positive return. Afterward, Lemssouguer brought in trader Ardacan Celebi from Deutsche Bank—also a graduate of France’s prestigious math schools. Celebi built Arini’s so-called “risk mitigation engine,” which integrates derivatives, bonds, and ETFs to absorb market shocks, allowing the fund to maintain offensive positions amid volatility. “Maximum drawdown is what can knock you out,” Celebi said. Currently, Arini’s team consists of analysts and traders from countries including Afghanistan, Turkey, and Ukraine, working closely together. After reaching $4 billion in assets, Arini's main fund closed to external investors. The company is now expanding aggressively into collateralized loan obligations (CLOs) and private credit—these businesses carry lower fees than hedge funds but have greater scale potential. About 60% of its fundraising comes from North America. Model Controversy: Can Concentrated Collaboration Withstand Market Stress? In terms of operational structure, Arini is very different from multi-strategy platforms like Citadel. The latter has multiple rival teams acting independently, while all Arini funds share one research team of 20 industry analysts, with unified information and collaborative judgement. Lemssouguer believes this model enables the company to seize investment opportunities more quickly. But critics point out potential risks: all funds’ positions may be highly correlated, and when markets change dramatically, risks could erupt all at once. Also, Arini’s “risk mitigation engine” has yet to be tested by a prolonged market downturn. In the face of widespread doubts, Lemssouguer maintains his usual unconventional stance. “Young age, being an outsider and a nontraditionalist, keeps me from being arrogant about the markets,” he said. Risk Warning and Disclaimer The market bears risks; investment should be cautious. This article does not constitute personal investment advice and does not take into account individual users' specific investment objectives, financial situation or needs. Users should consider whether any opinions, viewpoints, or conclusions in this article are suitable for their particular situation. Anyone who invests based on this article does so at their own risk.