Baker BROS. Portfolio Moves
Baker BROS. Advisors LP Significantly Boosts Biotech Stakes and Initiates New Position in Q4
Key Points
In IDEAYA Biosciences, Baker BROS. Advisors LP bought an additional 343,382 shares in Q4, taking its stake to 3,618,826 shares; the stock also ranked as the firm’s 20th-largest holding and represented about 4.13% of Baker BROS.’s investment portfolio (as reported in its filing).
Other IDEAYA investors reported in the same 13F-based coverage included Farther Finance Advisors LLC, which increased its position by 171.1% to 919 shares valued at about $32,000 (after buying 580 additional shares).
For Kodiak Sciences, Baker BROS. Advisors LP added 2,608,696 shares in the fourth quarter and held about 37.55% of the company; the coverage also notes Kodiak was the firm’s 11th-largest position in its portfolio.
Analyst price targets cited for Ionis Pharmaceuticals included: TD Cowen reissued a “buy” with a $108.00 price objective; HC Wainwright reissued a “buy” with a $125.00 objective; and Needham & Company raised its target from $103.00 to $105.00 (also reiterating a “buy”).
For Jade Biosciences (JBIO), specific analyst actions reported included HC Wainwright increasing its target from $45.00 to $55.00 (buy); BTIG raising its target from $39.00 to $74.00 (buy); Wall Street Zen cutting the stock from “hold” to “sell”; William Blair upgrading to a “strong-buy”; and Wedbush raising its target from $34.00 to $45.00 (outperform).
Baker BROS. Advisors LP quietly deepened its bet on clinical-stage biotech in the fourth quarter of 2025, adding shares across four companies and opening a brand-new position in Jade Biosciences. The moves, revealed in a February 2026 SEC filing, pushed the firm's total portfolio value to roughly $17.08 billion at year-end, according to SEC 13F Filing.
The New York-based fund, run by brothers Julian and Felix Baker, raised its IDEAYA Biosciences stake by 10.5% to 3,618,826 shares worth about $125.1 million. It also tripled down on Ionis Pharmaceuticals, boosting that position by 216.1%. The moves signal a sharp focus on precision oncology and autoimmune disease, two of biotech's hottest battlegrounds.
Baker BROS. Bets Big on IDEAYA and Kodiak Sciences
Baker BROS. added 343,382 IDEAYA Biosciences shares in Q4, making the stock its 20th-largest holding at about 4.13% of its portfolio, according to Ticker Report. Other institutions followed suit. Antipodes Partners and Russell Investments also added IDEAYA shares. Even Farther Finance Advisors LLC joined in, buying 580 additional shares — a 171.1% jump — though its total position came to just 919 shares worth about $32,000.
The firm's Kodiak Sciences move was even bolder. Baker BROS. added 2,608,696 shares, lifting its total to 19,919,186 — worth roughly $556.9 million and equal to about 37.6% of Kodiak's entire share count, according to Watchlist News. That level of ownership is rare for a hedge fund. It moves Baker BROS. closer to an owner than an outside investor, and makes Kodiak a likely target in any future merger talks.
Ionis Pharmaceuticals Gets a 216% Stake Surge
Baker BROS. made its most dramatic move in Ionis Pharmaceuticals, buying enough shares to grow its position by 216.1%. The firm ended Q4 holding 1,791,841 shares worth about $141.8 million. The surge drew attention from Wall Street analysts, who lined up with buy calls.
TD Cowen reissued a "buy" rating with a $108 price target. HC Wainwright did the same with a $125 target. Needham & Company raised its target from $103 to $105, also keeping a "buy" rating, according to Ticker Report. The three firms point to Ionis's RNA-targeting drug pipeline as the core reason for optimism.
Jade Biosciences Draws a New Baker BROS. Position
Baker BROS. opened a fresh position in Jade Biosciences, buying 1,641,137 shares worth roughly $25.3 million. Jade's lead drug, JADE101, targets a protein called APRIL to treat IgA nephropathy — a kidney disease where the immune system attacks the kidneys. In early June 2026, Phase 1 interim data showed 70% sustained reductions in a key disease marker, according to SEC 13F Filing.
Analysts split sharply on the stock. HC Wainwright raised its target from $45 to $55. BTIG nearly doubled its target, going from $39 to $74. William Blair upgraded Jade to "strong-buy." Wedbush lifted its target from $34 to $45. But Wall Street Zen cut the stock from "hold" to "sell," arguing the price had run ahead of its fair value, according to Watchlist News.
IDEAYA Raises $345 Million to Fund Its Cancer Pipeline
IDEAYA Biosciences closed a $345 million public offering in June 2026, funding its antibody-drug conjugate and synthetic lethality programs. Synthetic lethality is a strategy that kills cancer cells by targeting specific genetic weak spots. IDEAYA's focus is on uveal melanoma, a rare eye cancer driven by GNAQ and GNA11 gene mutations.
IDEAYA CEO Yujiro Hata said the company had "a strong quarter of clinical execution" and filed two new investigational drug applications in early 2026. The cash gives IDEAYA a runway into 2030. Meanwhile Jade Biosciences raised $172.5 million of its own to push JADE101 into mid-stage trials, according to SEC 13F Filing. Both companies now have the funds to reach potential approval by 2027 or 2028.
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