Despite the firm’s success, information about its founders and performance is hard to come by. Baker Bros. has no website and the brothers assiduously avoid the press. The brothers didn’t respond to repeated phone messages for comment on their net worth and strategy.

Rare details have emerged, such as when Felix bought one of the largest mansions in Manhattan for $45 million. The New York Post reported in 2017 that the West Village property, previously home to a children’s charity, would undergo a massive renovation into a single-family residence.

What’s known is that brothers Julian, 53, and Felix, 50, grew up in Chicago’s Hyde Park neighborhood. Their father taught history at the University of Chicago and their mother sociology at DePaul University, according to a college questionnaire from their mother. Julian studied at Harvard University and then worked in the private-equity arm of Credit Suisse First Boston. Felix attended Stanford University, completed two years of medical school and got a Ph.D in immunology.

In 1994, the siblings started managing health-care investments for the Tisch family, which had turned theater chain Loews into a conglomerate. The Bakers created a standalone business in 2000 and by 2006, they oversaw about $1 billion, a large but not unwieldy sum for a biotech-investment firm.

The brothers maintained close ties to the Tisch clan. Until 2017, Baker Bros. offices were in the same 667 Madison Avenue skyscraper that’s home to Loews Corp., the Tisch holding company.

Lean Operation
The Bakers, now based in the Meatpacking district, run a lean operation. The firm’s 40 employees -- 16 of them investment professionals -- oversaw $17.3 billion at the start of 2018, according to a regulatory filing. That’s just five more investing staff than it employed in 2012, when it managed less than a fifth of that sum.

Filings from Yale provide snapshots of how they’ve performed.

Yale’s charitable foundation had $274 million invested in 667 LP, a Baker Bros. vehicle, in 2009, IRS filings show. That ballooned to $1.08 billion by 2016, the most recent filing year on record, a combination of new money and profits of $393 million.

The Bakers’ success has been built on sweeping advances in the science of genetics, a meteoric rise in biotech stocks and a period of frenzied dealmaking as large biopharmaceutical companies have snapped up smaller innovators.

Since the end of 2006, the Nasdaq Biotechnology Index has returned 345%, while the Nasdaq and S&P 500 indices have returned 298% and 181%, respectively.