Sio Capital Management provides portfolio management for pooled vehicles and portfolio management for institutions. The firm advises 2 private funds.
Sio Capital Management reports 6 clients. They include 4 other investment advisers and 2 pooled investment vehicles. Of its assets, 100.0% ($1.29B across 6 accounts) are managed with discretion. Of its clients, 50% are outside the U.S.
| Client type | Clients | Assets |
|---|---|---|
| Pooled investment vehicles | 33% | 53% |
| Other investment advisers | 67% | 47% |
Client breakdown and activity details
| Client type | Clients | Regulatory AUM | AUM share | Avg. per client |
|---|---|---|---|---|
| Pooled investment vehicles | 2 | $685M | 53.0% | $343M |
| Other investment advisers | Fewer than 5 | $608M | 47.0% | $152M |
| Total | 6 | $1.29B | 100% | — |
- Clients
- 2
- Regulatory AUM
- $685M
- AUM share
- 53.0%
- Avg. per client
- $343M
- Clients
- Fewer than 5
- Regulatory AUM
- $608M
- AUM share
- 47.0%
- Avg. per client
- $152M
Total
- Clients
- 6
- Regulatory AUM
- $1.29B
- AUM share
- 100%
- Avg. per client
- —
- Clients outside the U.S.
- 50%
- Clients advised without assets under management last fiscal year
- 0
- Private funds advised
- 2
Sio Capital Management is paid through a percentage of assets under management and performance-based fees; its fees and minimums are set out in its brochures on the SEC website.
Michael Castor owns 75% or more of Sio Capital Management. Judah Drillick is CEO; the leadership team includes Chief Compliance Officer Jin Lee. It has 13 employees, 7 of them in advisory roles.
Leadership
- Judah DrillickChief Executive Officer
- Jin LeeChief Compliance Officer
- Michael CastorManaging Member
Staff
- 13 employees
- 7 in advisory functions
- Owns 75% or more of Sio Capital Management, LLC
Michael Castor
Control person · since March 2006
Sio Capital Management’s regulatory assets grew 1.5× from $859M (March 2021) to $1.29B (March 2026); clients fell from 7 to 6 and employees from 14 to 13.
Figures from each annual filing
| Filed | Regulatory AUM | Clients | Employees | Offices |
|---|---|---|---|---|
| March 2026 | $1.29B | 6 | 13 | 2 |
| March 2025 | $1.14B | 2 | 14 | 2 |
| March 2024 | $1.41B | 7 | 14 | 2 |
| March 2023 | $1.07B | 6 | 13 | 2 |
| March 2022 | $817M | 8 | 13 | 2 |
| March 2021 | $859M | 7 | 14 | 2 |
Besides its headquarters, Sio Capital Management has 1 office (1 private residence, listed without an address), with 1 listed address in New York.
New York · 1 listed address
- 600 Third Avenue, 2nd Floor, New YorkHQ
Contact and registration details
- Legal name
- Sio Capital Management, LLC
- Headquarters
- 600 Third Avenue, 2nd Floor, New York, NY 10016
- Website
- siocapital.com
- Phone
- 212-601-9792
- SEC file
- 801-78021
- Structure
- Delaware LLC
- Fiscal year end
- December
Sio Capital Management uses Morgan Stanley ($536M, 90%) and BNP Paribas Securities ($61.1M, 10%) as custodians for its separately managed accounts. Sio Capital Management has custody of client assets.
- Morgan StanleyMorgan Stanley & Co. LLC · New York, NY · $536M90%
- BNP Paribas SecuritiesBNP Paribas Securities Corp. · New York, NY · $61.1M10%
At year end, Sio Capital Management’s separately managed accounts were mostly in stocks (99%). Its reported 13F holdings for the quarter ended 30 June 2026 total $604M across 59 positions; the largest are Anteris Technologies Global (9.0%), Cencora Inc. (8.1%) and Maximus Inc. (6.4%).
What the accounts hold
- Stocks99%
- Exchange-traded equities98%
- Non-exchange-traded equities1%
- Other1%
- Derivatives1%
Reported 13F holdings
- $604M
- Reported 13F value
- 59
- Positions
- 48.6%
- In the 10 largest
- −13.3%
- Value vs. prior quarter
- Anteris Technologies Global9.0%
- Cencora Inc.8.1%
- Maximus Inc.6.4%
- Allogene Therapeutics Inc.4.6%
- Globus Med Inc. · CL A3.9%
- Gsk PLC · Sponsored ADR3.8%
- Tyra Biosciences Inc.3.7%
- Waystar Hldg Corp.3.1%
- Sellas Life Sciences Group IPut3.0%
- Ideaya Biosciences Inc.3.0%
Together, the ten largest are 48.6% of reported value.
How many clients does Sio Capital Management have?
Sio Capital Management has 6 clients and manages $1.29 billion for them, as of March 2026. They include 4 other investment advisers and 2 pooled investment vehicles.
Source: Form ADV Part 1A, Items 5.D and 5.F, filed 18 March 2026
What services does Sio Capital Management offer?
Sio Capital Management provides portfolio management for pooled vehicles and portfolio management for institutions.
Source: Form ADV Part 1A, Item 5.G, from the SEC's 2 October 2026 data file
Which custodians does Sio Capital Management use?
Sio Capital Management’s separately managed account assets are held at Morgan Stanley & Co. LLC (New York, NY), with $536M and BNP Paribas Securities Corp. (New York, NY), with $61.1M. Only custodians holding at least a tenth of those assets are named.
Source: Form ADV Part 1A, Schedule D, Section 5.K.(3), filed 18 March 2026
How many financial advisors does Sio Capital Management have?
Sio Capital Management has 0 investment adviser representatives registered with state securities authorities, out of 13 employees, and 7 perform investment advisory functions. None are registered representatives of a broker-dealer or licensed insurance agents.
Source: Form ADV Part 1A, Items 5.A and 5.B, from the SEC's 2 October 2026 data file
What does Sio Capital Management invest in?
At the end of its last fiscal year, Sio Capital Management’s separately managed accounts held 98% exchange-traded equities, 1% non-exchange-traded equities and 1% derivatives. It advises 2 private funds.
Source: Form ADV Part 1A, Items 5.K.(1) and 7.B, from the SEC's 2 October 2026 data file
Who owns Sio Capital Management?
Sio Capital Management’s direct owner is Michael Castor (75% or more).
Source: Form ADV Part 1A, Schedules A and B, filed 18 March 2026
How does Sio Capital Management get paid?
Sio Capital Management is paid through a percentage of assets under management and performance-based fees. Its Form ADV lists no commissions among how it is paid.
Source: Form ADV Part 1A, Item 5.E, from the SEC's 2 October 2026 data file
How do I contact Sio Capital Management?
Sio Capital Management’s main office is at 600 Third Avenue, 2nd Floor, New York, NY 10016. Its phone number is 212-601-9792. Its website is siocapital.com.