Fee-only adviser · Madison, WI
Isthmus Partners, LLC
Isthmus Partners, LLC is a fee-only investment adviser registered with the U.S. Securities and Exchange Commission, with its main office in Madison, Wisconsin. On its latest Form ADV, filed January 23, 2026, it reports $1.4B in regulatory assets under management, 357 individual clients and 8 employees who give investment advice. It reports no commission compensation, is not registered as a broker-dealer and does not act as an insurance agent.
Key facts from Form ADV
| Registration | SEC-registered |
|---|---|
| Firm CRD number | 171279 · SEC file 801-79683 |
| Office | 1 South Pinckney Street Suite 800 Madison, WI 53703 |
| Phone | (608) 729-0949 |
| Website | www.isthmuspartnersllc.com |
| Regulatory assets under management | $1.4B ($1.4B discretionary) |
| Individual clients | 149 non-high-net-worth, 208 high-net-worth |
| Financial planning clients | 251-500 |
| How it charges | Percentage of assets, Hourly, Fixed fee |
| Services | Financial planning, Portfolio management, Educational seminars |
| Employees | 17 |
| Disciplinary disclosures | None reported |
| Latest Form ADV filing | January 23, 2026 |
Source: the firm’s Form ADV Part 1A as published by the SEC’s Investment Adviser Public Disclosure database, data as of November 6, 2026. Figures are self-reported by the firm.
What this means for you
- It offers hourly or fixed-fee arrangements, so you may be able to pay for a plan without handing over your investments.
- It also charges a percentage of assets managed for ongoing investment management.
- Most of its individual clients are high-net-worth, which on Form ADV means they meet the SEC’s qualified-client or qualified-purchaser test: broadly, more than $1 million managed by the adviser or a net worth above $2 million, with the thresholds indexed for inflation.
- It provides financial planning services, not only portfolio management.
- It sponsors or manages a wrap fee program; ask what the bundled fee covers.
- It reports no disciplinary history on Form ADV.
Before you hire any adviser
Read the firm’s Form ADV Part 2 brochure on its SEC record: it sets out fees, minimums, conflicts of interest and who will manage your money. Ask whether the firm acts as a fiduciary for all of your accounts, how it is paid in total, and who holds your assets. Our guide to choosing a financial adviser lists the questions to ask.
Other fee-only advisers in Madison
- Madison Partners $1.3B
- Resonant Capital Advisors, LLC $3.0B
- Enrich Financial Partners LLC $557M
- T. Anton Investment House, Inc. $367M
- Atlatl Advisers $393M
- Calculated Wealth $201M
See all 23 fee-only advisers in Madison →
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