Isthmus Partners provides financial planning, portfolio management for individuals and small businesses, portfolio management for institutions, educational seminars, business succession planning, estate planning, family office services, insurance, and philanthropic planning. Financial planning was provided to 251–500 clients last fiscal year.
Isthmus Partners reports 381 clients. They include 208 high-net-worth individuals, 149 individual clients, and 14 pension and profit-sharing plans. Of its assets, 94.6% ($1.36B across 1,504 accounts) are managed with discretion; $77.3M across 390 accounts are not. A wrap fee program the firm both sponsors and manages holds $3.98B. Of its clients, 1% are outside the U.S.
| Client type | Clients | Assets |
|---|---|---|
| Individuals (other than HNW) | 39% | 10% |
| High-net-worth individuals | 55% | 79% |
| Pension and profit-sharing plans | 4% | 2% |
| Charitable organizations | 1% | 7% |
| Corporations and other businesses | 1% | 2% |
Client breakdown and activity details
| Client type | Clients | Regulatory AUM | AUM share | Avg. per client |
|---|---|---|---|---|
| Individuals (other than HNW) | 149 | $138M | 9.6% | $926K |
| High-net-worth individuals | 208 | $1.14B | 79.4% | $5.49M |
| Pension and profit-sharing plans | 14 | $35.7M | 2.5% | $2.55M |
| Charitable organizations | 5 | $96.4M | 6.7% | $19.3M |
| Corporations and other businesses | 5 | $26.1M | 1.8% | $5.22M |
| Total | 381 | $1.44B | 100% | $3.78M |
- Clients
- 149
- Regulatory AUM
- $138M
- AUM share
- 9.6%
- Avg. per client
- $926K
- Clients
- 208
- Regulatory AUM
- $1.14B
- AUM share
- 79.4%
- Avg. per client
- $5.49M
- Clients
- 14
- Regulatory AUM
- $35.7M
- AUM share
- 2.5%
- Avg. per client
- $2.55M
- Clients
- 5
- Regulatory AUM
- $96.4M
- AUM share
- 6.7%
- Avg. per client
- $19.3M
- Clients
- 5
- Regulatory AUM
- $26.1M
- AUM share
- 1.8%
- Avg. per client
- $5.22M
Total
- Clients
- 381
- Regulatory AUM
- $1.44B
- AUM share
- 100%
- Avg. per client
- $3.78M
- Clients outside the U.S.
- 1%
- Clients advised without assets under management last fiscal year
- 0
- Private funds advised
- 0
- Financial planning clients last fiscal year
- 251–500
Isthmus Partners charges 0.60%–1.25% a year for its Counseled Portfolios. The whole portfolio is charged at the rate of its band. The fee has a $25,000 annual minimum. The brochure also prices one other service, listed under fee details.
| Asset band | Annual rate |
|---|---|
| $0–$2M | 1.25% |
| $2M–$5M | 1.00% |
| $5M–$10M | 0.80% |
| $10M and above | 0.60% |
Fee details and sources
Other fees
- Financial Planning Services
- Financial planning is a fixed fee from $500 to $5,000, depending on scope, or hourly at $250 an hour.
Frank Gambino owns 25% to 50% of Isthmus Partners. The leadership team of Isthmus Partners includes Chief Investment Officer David Hackworthy and Chief Compliance Officer Gery Sadzewicz. It has 17 employees, 8 of them in advisory roles.
Leadership
- Gery SadzewiczChief Compliance Officer
- Jeremy BaierMember
- Ryan CobbCOO
- Joseph EdelsteinMember
- Frank GambinoChief Equity Strategist
- Noel GoeddelMember
- David HackworthyChief Investment Officer
- Joel McNeilDirector
- Thomas SimpsonMember
- Victor RodriguezMember
Investment adviser representatives
9 representatives listed in the SEC register as of 9 October 2026.
- Brandon A Cloete
- Frank Joseph Gambino
- Noel David Goeddel
- David A Hackworthy
- Eric Alvin Knudson
- Joel Carter McNeil
- Margaret Elizabeth McNeil
- Victor Enrique Rodriguez
- Rebecca A Wiegand
Staff
- 17 employees
- 8 in advisory functions
- 7 state-registered reps
- Owns 25% to 50% of Isthmus Partners, LLC
Frank Gambino
Control person · since May 2014
- Owns 25% to 50% of Isthmus Partners, LLC
David Hackworthy
Control person · since May 2014
- Owns 10% to 25% of Isthmus Partners, LLC
Joel McNeil
since May 2014
- Owns 5% to 10% of Isthmus Partners, LLC
Victor Rodriguez
since May 2014
Isthmus Partners’ regulatory assets grew 1.8× from $780M (March 2021) to $1.44B (January 2026); clients rose from 312 to 381 and employees from 14 to 17.
Figures from each annual filing
| Filed | Regulatory AUM | Clients | Employees | Offices |
|---|---|---|---|---|
| January 2026 | $1.44B | 381 | 17 | 1 |
| July 2025 | $1.3B | 364 | 16 | 2 |
| April 2024 | $1.11B | 346 | 16 | 1 |
| March 2023 | $977M | 336 | 15 | 1 |
| February 2022 | $953M | 333 | 15 | 1 |
| March 2021 | $780M | 312 | 14 | 1 |
Besides its headquarters, Isthmus Partners has 0 offices, with 1 listed address in Wisconsin.
Wisconsin · 1 listed address
- 1 South Pinckney Street, Suite 800, MadisonHQ
Contact and registration details
- Legal name
- Isthmus Partners, LLC
- Headquarters
- 1 South Pinckney Street, Suite 800, Madison, WI 53703
- Website
- isthmuspartnersllc.com
- Phone
- 608-729-0949
- SEC file
- 801-79683
- Founded
- 2014
- Structure
- Wisconsin LLC
- Fiscal year end
- December
Isthmus Partners uses Charles Schwab ($1.31B, 96%), State Street ($24M, 2%) and Bmo Harris ($17.3M, 1%), among others, as custodians for its separately managed accounts. Isthmus Partners has custody of $853M in client assets for 149 clients.
- Charles SchwabCharles Schwab & Co., Inc. · San Francisco, CA · $1.31B96%
- Godfrey & KahnGodfrey & Kahn · Milwaukee, WI · $11.7M1%
- Bmo HarrisBmo Harris · Madison, WI · $17.3M1%
- State StreetState Street · Madison, WI · $24M2%
At year end, Isthmus Partners’ separately managed accounts were mostly in stocks (67%) and bonds (11%). Its reported 13F holdings for the quarter ended 30 June 2026 total $1.03B across 226 positions; the largest are iShares TR (4.7%), Apple Inc. (2.6%) and Alphabet Inc. (2.4%).
What the accounts hold
- Stocks67%
- Funds7%
- Bonds11%
- State and local bonds7%
- U.S. government and agency bonds4%
- Cash7%
- Other8%
- Fdic bank certificates of deposit.8%
Reported 13F holdings
- $1.03B
- Reported 13F value
- 226
- Positions
- 23.8%
- In the 10 largest
- +8.5%
- Value vs. prior quarter
- iShares TR · Core MSCI Eafe4.7%
- Apple Inc.2.6%
- Alphabet Inc. · Cap Stk CL A2.4%
- Applied Matls Inc.2.4%
- Broadcom Inc.2.1%
- Visa Inc. · Com CL A2.0%
- Johnson & Johnson2.0%
- Bank OF NY Mellon Corp.1.9%
- Rockwell Automation Inc.1.8%
- WW Grainger Inc.1.8%
Together, the ten largest are 23.8% of reported value.
How many clients does Isthmus Partners have?
Isthmus Partners has 381 clients and manages $1.44 billion for them, as of January 2026. They include 208 high-net-worth individuals, 149 individual clients, and 14 pension and profit-sharing plans.
Source: Form ADV Part 1A, Items 5.D and 5.F, filed 23 January 2026
What services does Isthmus Partners offer?
Isthmus Partners provides financial planning, portfolio management for individuals and small businesses, portfolio management for institutions, educational seminars, business succession planning, estate planning, family office services, insurance, and philanthropic planning.
Source: Form ADV Part 1A, Item 5.G, from the SEC's 2 October 2026 data file; Part 2A brochure, Item 4
How much does Isthmus Partners charge?
Isthmus Partners charges 0.60%–1.25% a year for its Counseled Portfolios. The whole portfolio is charged at the rate of its band. The fee has a $25,000 annual minimum.
Source: ISTHMUS PARTNERS APPENDIX 1 WRAP FEE BROCHURE, filed 23 January 2026
Which custodians does Isthmus Partners use?
Isthmus Partners’ separately managed account assets are held at Charles Schwab & Co., Inc. (San Francisco, CA), with $1.31B, State Street (Madison, WI), with $24M, Bmo Harris (Madison, WI), with $17.3M and Godfrey & Kahn (Milwaukee, WI), with $11.7M. Only custodians holding at least a tenth of those assets are named.
Source: Form ADV Part 1A, Schedule D, Section 5.K.(3), filed 23 January 2026
How many financial advisors does Isthmus Partners have?
Isthmus Partners has 7 investment adviser representatives registered with state securities authorities, out of 17 employees, and 8 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 Isthmus Partners invest in?
At the end of its last fiscal year, Isthmus Partners’ separately managed accounts held 67% exchange-traded equities, 8% other, 7% state and local bonds, 7% registered funds (mutual funds, ETFs, BDCs), 7% cash and equivalents and 4% U.S. government and agency bonds. The 8% other category is described as: Fdic Bank Certificates of Deposit.
Source: Form ADV Part 1A, Items 5.K.(1) and 7.B, from the SEC's 2 October 2026 data file
Who owns Isthmus Partners?
Isthmus Partners’ direct owners are Frank Gambino, David Hackworthy, Victor Rodriguez and Joel McNeil, each holding 50% or less.
Source: Form ADV Part 1A, Schedules A and B, filed 23 January 2026
How does Isthmus Partners get paid?
Isthmus Partners is paid through a percentage of assets under management, hourly charges and fixed fees. Its Form ADV lists no commissions or 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
Is Isthmus Partners registered with the SEC?
Yes, Isthmus Partners has been registered with the SEC as an investment adviser since 19 May 2014. Its CRD number is 171279 and its SEC file number is 801-79683.
Source: Form ADV Part 1A, Item 1, filed 23 January 2026; IAPD firm record
How do I contact Isthmus Partners?
Isthmus Partners’ main office is at 1 South Pinckney Street, Suite 800, Madison, WI 53703. Its phone number is 608-729-0949. Its website is isthmuspartnersllc.com.