The mysterious billionaire boss at Jane Street smashing trading records

NEW YORK - Mr Rob Granieri took to the dance floor with long hair flowing from his fedora, shiny jacket glinting and a boutonniere bursting with colour.

The wealthy recluse showed off his moves after platters of caviar and bacon-wrapped shrimp swirled through the room to celebrate the Scarlet Pearl, his casino hulking over Mississippi’s Biloxi Bay. The disco-bright veneer gave the revellers no hint of the 53-year-old billionaire’s hidden reality.

Far away from slot machines and roulette, this is the man piling up billions of dollars as the last founder standing at Jane Street – now the world’s most lucrative trading house.

At his day job on Wall Street, Mr Granieri slips back into the schlubby wardrobe that is the norm at the 25-year-old firm. Soft-spoken, he often goes unrecognized within the company, where he officially has no title. His profile in the employee directory stands out because of its missing headshot.

But in 2025, the company’s cherished obscurity has been shredded, nudging Mr Granieri closer to the thing he most detests – the spotlight.

Legal wrangles and ballooning profits have drawn global attention. The company notched US$10.1 billion (S$13 billion) of trading revenue in the second quarter, trouncing the biggest banks. Its haul for the first half of 2025 eclipsed US$17 billion – almost on a par with its full-year record set in 2024.

A year ago, the firm was best known as the launchpad of Sam Bankman-Fried, who went on to found cryptocurrency exchange FTX before ending up in prison.

But then came Jane Street’s bruising legal battle with a pair of departing traders. When the firm sued them in 2024 for allegedly stealing an “immensely valuable” strategy, it drew attention from an Indian regulator, which accused the company of rigging the world’s largest options market. The firm has vowed to fight those claims.

By then, Mr Granieri was already facing his own embarrassment over being duped into funding a plot for a military coup in Africa.

The events have been a jarring experience for the firm’s army of mathematicians and engineers, who are more comfortable geeking out over anomalies in markets to get rich.

In the past, management’s main anxiety was keeping a lid on executives’ swelling wealth.

In 2018, a senior Jane Street partner violated that protocol by arranging for Cardi B to perform at his son’s bar mitzvah in New York’s trendy TAO Downtown.

Unlike his peers who snap up trophy homes, Mr Granieri has long preferred to live in rental housing to avoid the headaches of owning property. Still, a landlord once took him to court after Mr Granieri missed reminders for an unpaid US$10,372 bill.

Mr Granieri grew up just outside Norristown, Pennsylvania, an old mill town. For long-timers, the best known connection to the family is his parents’ former business, a once-popular banquet hall called Chateau Granieri.

According to his high school yearbook, Granieri showed a fondness for Metallica and “talks with radicals and libertarians”. He also harboured ambitions to make a lot of money.

After graduating from the University of Pennsylvania in 1992, he turned down an opening at a New Jersey operation that wanted him to cold-call people to pitch stocks.

With no other offers, he printed a stack of résumés and dropped them off on each floor of Philadelphia’s tallest buildings. That is how he scored a job at Mr Jeff Yass’ Susquehanna International Group, the quant-trading firm that was quietly becoming a market behemoth.

By the time Mr Granieri quit at 27, he was pulling in US$700,000 a year and itching for change. He bonded with a colleague, Mr Mike Jenkins, over their mutual dislike for a middle manager. The pair, along with another trader, Mr Tim Reynolds, set out in 1999 to build what would become Jane Street.

Jane Street, Citadel Securities and Hudson River Trading are part of a rising class of market-making firms that have built expansive high-speed systems to carry out investor trades, benefiting from electronification and the rapid growth of exchange-traded funds (ETFs).

Jane Street alone accounted for 24 per cent of all US-listed primary ETF trading volume in 2024. It handles over 90,000 products across more than 240 exchanges, filling voids left as stricter capital rules led investment banks to pull back.

It has found a lucrative niche in capturing brief mismatches in prices between plain-vanilla assets and their derivatives. And its profits are soaring above the pack, boosted by proprietary trading with its own capital – a stockpile that that has grown to US$53 billion. By the second quarter, the pace of revenue had quickened so dramatically that the firm earned in two weeks what took all year a decade ago. BLOOMBERG