Millburn Ridgefield LLC
Millburn Ridgefield promotes Michael Soss to CIO
Summary: Millburn Ridgefield announced that Michael Soss was promoted to Chief Investment Officer, according to the firm's official March 2025 update. This is a personnel and governance backfill item rather than breaking news.
Why it matters: The promotion may matter to due-diligence readers as a public leadership-continuity and investment-governance signal at a quantitative investment manager.
Summary
Millburn Ridgefield announced that Michael Soss was promoted to Chief Investment Officer, according to the firm’s official March 2025 update. The official source and Millburn’s public site support the manager identity, source access, and event framing; no existing Millburn/Soss duplicate was found in the site content.
This is seed/backfill coverage for a manager profile or governance feed, not breaking news. It does not adopt Millburn’s promotional language or imply an assessment of Soss, Millburn’s strategy, or future performance.
Why it matters
For due-diligence readers, a CIO promotion is relevant as a public leadership-continuity and investment-governance signal. It can prompt ordinary follow-up questions about investment-decision authority, committee structure, strategy oversight, and how a manager communicates leadership transitions.
The update does not by itself show investment quality, performance, client retention, or operational change. It is public context only, not a recommendation or endorsement.
Source notes
- Official Millburn source: https://millburn.com/insights/millburn-promotes-michael-soss-to-cio
- Millburn public site: https://millburn.com/
- SEC EDGAR filer page for 13F context: https://www.sec.gov/edgar/browse/?CIK=1294571
- Verifier note: official page returned HTTP 200 and supported the title/body metadata for the CIO promotion; identity mapped to MILLBURN RIDGEFIELD LLC with CRD 148870 / SEC file 801-60938. The item is dated March 2025 and should remain clearly labeled as backfill/personnel-governance context.
9AT filing context
Public ADV/profile context maps MILLBURN RIDGEFIELD LLC to CRD 148870 / SEC file 801-60938, with about $8.7 billion in reported regulatory AUM/profile scale. The profile output shows 59 employees, 6 private funds, separately managed account activity, and public website domains millburn.com and millburncorp.com.
EDGAR 13F history for Millburn Ridgefield LLC /DE/ under CIK 1294571 returned public filings including the 2025-09-30 period, filed 2025-10-30, with 38 information-table rows and about $4.2 billion in parsed listed-securities value. The two prior returned periods were 2025-06-30, also about $4.2 billion, and 2025-03-31, about $4.1 billion.
That filing context is only background for public identity, registration, and listed-securities reporting. It does not validate the CIO promotion, assess leadership quality, show total AUM, or indicate performance.
What to watch
Watch for future Millburn ADV amendments, 13F filings, public strategy commentary, team pages, or client-facing materials that clarify whether the CIO promotion coincides with changes in investment governance, risk oversight, product focus, or external communications.