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- Custodian
- Assetmark · Pershing · SEI
- Clients
- Retail
- Platforms
- --
- Established Date
- 02-05-1988
- Office Locations
- 1
Office Locations
About OAK Brook Advisors, LLC
Oak Brook Advisors, Ltd. is an Illinois-based RIA affiliated with Oak Brook Financial Group, focused on retirement-oriented planning and wealth management. The firm advises on 401(k)/IRA rollovers, retirement income maximization, estate planning, and insurance and fee-based investment strategies, including annuities. Co-principal W. Russell Grzywinski (advisor since 1982) is a Bank On Yourself™ Professional.
Reported data analysis
What the numbers show
Of the latest reported AUM, 0.0% is discretionary and 100.0% is non-discretionary.
The firm reports 1 advisory representatives and 128 clients, or 128 clients per representative. That equates to $132.8K in reported AUM per client.
The profile lists 1 reported office location and 38 years in operation. The source data was last updated on March 26, 2026. Figures reflect reported regulatory data and may not include subsequent changes.
Team overview
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Available data coverage
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- Custodian
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Owner & Executives
WALTER RUSSELL GRZYWINSKI
Chief Compliance Officer, President
- CRD
- #1082642
- Ownership
- 75% or more
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No AUM history available
| Category | Assets | AVG. Account size |
|---|---|---|
| Discretionary | $0 | -- |
| Non-Discretionary | $17,000,000 | -- |
| Total | $17,000,000 | -- |
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Separately Managed Accounts
SMA allocation detail is available
OAK Brook Advisors, LLC has reported separately managed account data across 1 asset class. AdvizorPro provides the associated asset values, allocation percentages, and exportable breakdown.