Alumis Inc. Form 13D/A Filing Analysis: Institutional Investor Implications

Based on my comprehensive research of SEC filings, I have identified the recent Form 13D/A filings for Alumis Inc. (NASDAQ: ALMS) and can provide a detailed analysis of their implications for institutional investors.

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Alumis Inc. has recently experienced significant shareholder activity reflected in multiple Schedule 13D and 13G filings. The most recent and significant filing is

, filed on by Foresite Capital and affiliated entities [0].

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The Foresite Capital group, led by James B. Tananbaum, is the largest beneficial owner of Alumis Inc. stock. The January 12, 2026 amendment reveals critical changes:

Reporting Person	Shares Owned	Ownership %	Voting Power
James B. Tananbaum (aggregate)	16,189,804	14.1%	Shared/Sole
Foresite Capital Fund V, L.P.	5,702,536	5.0%	Sole
Foresite Capital Management V, LLC	5,896,995	5.1%	Sole
Foresite Capital Fund VI, L.P.	4,247,670	3.7%	Sole
Foresite Capital Opportunity Fund V, L.P.	2,908,332	2.5%	Sole

Percentages based on 114,824,231 total outstanding shares [0].

1. Dilution Adjustment
   : The Foresite group’s aggregate ownership percentage decreased by over 1% due to Alumis’ issuance of additional common stock through its January 2026 follow-on offering.

2. New Share Acquisitions in Follow-On Offering
   :
   • Foresite Capital Fund V, L.P.
     purchased
     117,647 shares
     at $17.00/share (approximately $2.0 million)
   • Foresite Capital Opportunity Fund V, L.P.
     purchased
     294,117 shares
     at $17.00/share (approximately $5.0 million) [0]

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A second significant institutional investor group is

, led by Managing General Partner , who serves on Alumis’ Board of Directors.

Reporting Person	Shares Owned	Ownership %
Srinivas Akkaraju (aggregate)	5,134,991	5.3%
Samsara BioCapital, L.P.	4,491,731	4.6%
Samsara Opportunity Fund, L.P.	643,260	0.7%

Based on 97,208,495 outstanding shares [0].

• On November 13, 2025, Samsara Opportunity Fund purchased 276,179 shares from Samsara BioCapital at $5.25/share in a private transaction
• The group engaged in open market sales of 33,460 shares at $5.28/share for limited partner redemptions
• Following these transactions, the group
  ceased to beneficially own greater than 5%
  of Alumis’ voting common stock [0]

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and affiliated entities filed on November 17, 2025, indicating a :

Shareholder	Shares Owned	Ownership %
venBio Global Strategic Fund IV, L.P.	4,619,803	4.8%
venBio Global Strategic GP IV, LLC	4,619,803	4.8%
Robert J. Adelman	4,619,803	4.8%
Corey S. Goodman	4,619,803	4.8%

Based on 96,857,569 outstanding shares [0].

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The Foresite Capital group’s

in the January 2026 follow-on offering demonstrates continued confidence in Alumis’ clinical development pipeline, despite dilution from the capital raise. The group’s 14.1% aggregate stake makes them the largest beneficial owner with significant influence over corporate governance [0].

Dr. Akkaraju’s dual role as both a

and positions Samsara BioCapital to have direct input on strategic decisions. However, the recent reduction below the 5% threshold may signal a rebalancing of their investment thesis [0].

• Schedule 13D filers
  (Foresite, Samsara) indicate
  active involvement
  or intent to influence control
• Schedule 13G filers
  (venBio) indicate
  passive investment intent
  with less than 5% ownership
• The distinction affects disclosure requirements and signals different investment time horizons [0]

The upsized public offering (17.65 million shares at $17.00/share, raising approximately $345 million) significantly diluted existing shareholders. Institutional investors must track

rather than absolute share counts to accurately assess their position [0].

Foresite Capital’s participation in the offering at the public offering price demonstrates:

• Support for the company’s capital raising strategy
• Willingness to maintain or increase their proportional stake
• Confidence in near-term catalysts and clinical milestones [0]

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Factor	Implication
Ownership Concentration	Top 3 institutional groups (Foresite, Samsara, venBio) collectively control approximately 24% of outstanding shares
Board Influence	Director-aligned investors (Samsara) hold board seats with active governance capabilities
Capital Raise Support	Major shareholders participated in the follow-on, signaling confidence
Threshold Monitoring	Samsara’s fall below 5% may indicate profit-taking or portfolio rebalancing
Dilution Awareness	Share count increases require ongoing adjustment of ownership calculations

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[0] SEC EDGAR - Alumis Inc. Schedule 13D/A Filings (https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0001847367&owner=include&count=40)

[1] Alumis Inc. Form 8-K filed January 9, 2026 (https://investors.alumis.com/static-files/0f62ecfe-8c10-482d-8d4d-284e080d645e)

[2] Alumis Inc. Form 424B5 Prospectus (https://www.sec.gov/Archives/edgar/data/1847367/000110465926002203/0001104659-26-002203-index.htm)