Why This Biotech Fund Increased Its Oruka Therapeutics Stake Amid a Staggering 500% Rally

Avidity Partners Management disclosed a buy of 100,000 shares of Oruka Therapeutics (NASDAQ:ORKA) in a May 13, 2026, SEC filing, with an estimated transaction value of $3.48 million based on quarterly average pricing.

What happened

Avidity Partners Management reported purchasing 100,000 additional shares of Oruka Therapeutics, according to a Securities and Exchange Commission (SEC) filing dated May 13, 2026. The estimated transaction value was $3.48 million, calculated using the average closing price during the first quarter of 2026. The fund's quarter-end position value in Oruka Therapeutics rose by $32.00 million, a figure that includes both the share increase and changes in market price.

What else to know

• This was a buy; the post-trade stake accounts for 11.77% of Avidity Partners Management LP's 13F reportable assets.
• Top five holdings after the filing:
  • NASDAQ:DNTH: $184.75 million (41.8% of AUM)
  • NASDAQ:ORKA: $52.02 million (11.77% of AUM)
  • NASDAQ:JBIO: $34.18 million (7.7% of AUM)
  • NYSEMKT:CATX: $23.59 million (5.3% of AUM)
  • NASDAQ:ELVN: $16.49 million (3.7% of AUM)
• As of May 12, 2026, Oruka Therapeutics shares were priced at $64.65, up 563.1% over the past year and significantly outperforming the S&P 500, which is instead up about 26%.

Company overview

Company snapshot

• Oruka develops monoclonal antibody therapeutics, with a pipeline that includes ORKA-001 and ORKA-002, targeting psoriasis (PsO) and other immunology and inflammation (I&I) indications.
• The firm operates a biotechnology business model focused on research and development, aiming to generate revenue through the eventual commercialization and licensing of proprietary therapeutics.
• It targets healthcare providers, pharmaceutical partners, and patients affected by autoimmune and inflammatory diseases.

Oruka Therapeutics is a clinical-stage biotechnology company specializing in innovative monoclonal antibody therapies for immunology and inflammation. With a lean workforce and a focused pipeline, the company is positioned to address unmet medical needs in psoriasis and related conditions. Its strategy emphasizes novel biologic development to achieve competitive differentiation in the biopharmaceutical sector.

What this transaction means for investors

Rather than trimming after a massive rally, Avidity added to a position that already represents nearly 12% of its reported portfolio, suggesting fairly high conviction.

The recent enthusiasm comes amid late-April Phase 2a psoriasis data for ORKA-001, where 63.5% of treated patients achieved complete skin clearance at Week 16. Management also said updated pharmacokinetic data continue to support the possibility of once-yearly dosing, which could become a major differentiator if future trials hold up. Oruka also announced a proposed $500 million public offering in April, likely aimed at funding larger trials and expanding its pipeline.

For long-term investors, the core question is whether ORKA-001 can continue producing best-in-class efficacy while maintaining durability and safety advantages against entrenched psoriasis competitors. If it can, the stock’s huge move over the past year may not be the end of the story.

Jonathan Ponciano has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.