Mack Investment Securities provides financial planning, portfolio management for individuals and small businesses, selecting other managers, publishing newsletters, and market timing. Financial planning was provided to 251–500 clients last fiscal year.
Mack Investment Securities reports 673 clients. They include 379 individual clients, 282 high-net-worth individuals, and 12 pension and profit-sharing plans. Of its assets, 70.9% ($215M across 729 accounts) are managed with discretion; $87.9M across 288 accounts are not.
| Client type | Clients | Assets |
|---|---|---|
| Individuals (other than HNW) | 56% | 21% |
| High-net-worth individuals | 42% | 76% |
| Pension and profit-sharing plans | 2% | 2% |
Client breakdown and activity details
| Client type | Clients | Regulatory AUM | AUM share | Avg. per client |
|---|---|---|---|---|
| Individuals (other than HNW) | 379 | $65M | 21.5% | $171K |
| High-net-worth individuals | 282 | $231M | 76.3% | $818K |
| Pension and profit-sharing plans | 12 | $6.83M | 2.3% | $569K |
| Total | 673 | $303M | 100% | $450K |
- Clients
- 379
- Regulatory AUM
- $65M
- AUM share
- 21.5%
- Avg. per client
- $171K
- Clients
- 282
- Regulatory AUM
- $231M
- AUM share
- 76.3%
- Avg. per client
- $818K
- Clients
- 12
- Regulatory AUM
- $6.83M
- AUM share
- 2.3%
- Avg. per client
- $569K
Total
- Clients
- 673
- Regulatory AUM
- $303M
- AUM share
- 100%
- Avg. per client
- $450K
- Clients outside the U.S.
- 0%
- Clients advised without assets under management last fiscal year
- 0
- Private funds advised
- 0
- Financial planning clients last fiscal year
- 251–500
Mack Investment Securities is paid through a percentage of assets under management, hourly charges, fixed fees (other than subscription fees) and commissions. The reviewed brochures do not disclose an asset-based fee rate. Read the SEC-filed brochure. The brochure also prices 2 other services, listed under fee details.
Fee details and sources
Other fees
- Consulting Services
- Consulting is billed hourly at $300 to $500, as a fixed fee of $2,000 to $8,000, or as 1.25% to 2.25% of assets under review.
- Financial Planning
- Financial planning is a one-time fixed fee of $2,000 to $8,000, an ongoing fixed fee of $800 to $5,000 per quarter, or $300 to $500 per hour with a two-hour minimum.
Stephen Walter Mack owns 75% or more of Mack Investment Securities. The leadership team of Mack Investment Securities includes President Stephen Walter Mack. It has 8 employees.
Leadership
- Stephen Walter MackTrustee Is President and CCO
Investment adviser representatives
8 representatives listed in the SEC register as of 9 October 2026.
- John Russell Budziak
- Norman Peter Chiodras
- Sheldon David Kaiz
- John Anthony Kelty III
- Kevin Edward Mack
- Michael Stephen Mack
- Stephen Walter Mack
- Steven Brian Milstein
Staff
- 8 employees
- 8 in advisory functions
- 6 state-registered reps
- 8 broker-dealer reps
- 6 insurance agents
- Owns 75% or more of Mack Investment Securities, Inc.
Stephen Walter Mack
Control person · since January 1986
Mack Investment Securities’ regulatory assets grew 1.6× from $186M (March 2021) to $303M (March 2026); clients were 673 in both filings and employees fell from 9 to 8.
Figures from each annual filing
| Filed | Regulatory AUM | Clients | Employees | Offices |
|---|---|---|---|---|
| March 2026 | $303M | 673 | 8 | 2 |
| March 2025 | $264M | 676 | 8 | 2 |
| May 2024 | $222M | 701 | 7 | 2 |
| March 2023 | $203M | 650 | 7 | 2 |
| July 2022 | $201M | 827 | 9 | 2 |
| March 2021 | $186M | 679 | 9 | 2 |
Besides its headquarters, Mack Investment Securities has 1 office, with 2 listed addresses in Illinois.
Illinois · 2 listed addresses
- 211 Waukegan Road, Ste 300, NorthfieldHQ
- 2001 Midwest RD, Oak Brook
Contact and registration details
- Legal name
- Mack Investment Securities, Inc.
- Headquarters
- 211 Waukegan Road, Ste 300, Northfield, IL 60093
- Website
- Not reported
- Phone
- 847-657-6600
- SEC file
- 801-29570
- Structure
- Illinois corporation
- Fiscal year end
- December
Mack Investment Securities uses Axos Clearing ($152M, 76%) and SEI Private Trust ($48.2M, 24%) as custodians for its separately managed accounts. Mack Investment Securities does not have custody of client assets.
- SEI Private TrustSEI Private Trust Co. · Oaks, PA · $48.2M24%
- Axos ClearingAxos Clearing LLC · Englewood, CO · $152M76%
At year end, Mack Investment Securities’ separately managed accounts were mostly in stocks (51%) and funds (24%).
What the accounts hold
- Stocks51%
- Funds24%
- Registered funds22%
- Pooled vehicles2%
- Bonds1%
- Cash24%
How many clients does Mack Investment Securities have?
Mack Investment Securities has 673 clients and manages $303 million for them, as of March 2026. They include 379 individual clients, 282 high-net-worth individuals, and 12 pension and profit-sharing plans.
Source: Form ADV Part 1A, Items 5.D and 5.F, filed 31 March 2026
What services does Mack Investment Securities offer?
Mack Investment Securities provides financial planning, portfolio management for individuals and small businesses, selecting other managers, publishing newsletters, and market timing.
Source: Form ADV Part 1A, Item 5.G, from the SEC's 2 October 2026 data file
Which custodians does Mack Investment Securities use?
Mack Investment Securities’ separately managed account assets are held at Axos Clearing LLC (Englewood, CO), with $152M and SEI Private Trust Co. (Oaks, PA), with $48.2M. Only custodians holding at least a tenth of those assets are named.
Source: Form ADV Part 1A, Schedule D, Section 5.K.(3), filed 31 March 2026
How many financial advisors does Mack Investment Securities have?
Mack Investment Securities has 6 investment adviser representatives registered with state securities authorities, out of 8 employees, and 8 perform investment advisory functions. 8 employees are registered representatives of a broker-dealer and 6 employees are 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 Mack Investment Securities invest in?
At the end of its last fiscal year, Mack Investment Securities’ separately managed accounts held 51% exchange-traded equities, 24% cash and equivalents, 22% registered funds (mutual funds, ETFs, BDCs), 2% pooled vehicles (private funds and similar) and 1% investment grade corporate bonds.
Source: Form ADV Part 1A, Items 5.K.(1) and 7.B, from the SEC's 2 October 2026 data file
Who owns Mack Investment Securities?
Mack Investment Securities’ direct owner is Stephen Walter Mack (75% or more).
Source: Form ADV Part 1A, Schedules A and B, filed 31 March 2026
How does Mack Investment Securities get paid?
Mack Investment Securities is paid through a percentage of assets under management, hourly charges, fixed fees and commissions. Its Form ADV lists no performance-based fees 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 Mack Investment Securities?
Mack Investment Securities’ main office is at 211 Waukegan Road, Ste 300, Northfield, IL 60093. Its phone number is 847-657-6600.