MainStreet Investment Group L.L.C. Wealth Management - Home


As of Monday, March 16, 2020, to help stop the spread of COVID-19, our offices will only be speaking with clients via telephone. We are asking you not to come into our office at this time.  This is for the safety of our clients, our employees and the community. Please do not enter our offices to speak with anyone, but instead give us a call. Please do not expect to be able to enter our offices.

Tomahawk office:

1411 N. 4th Street, Suite 103

Tomahawk, WI  54487



Thiensville office:

136 Green Bay Road

Thiensville, WI  53092


All client reviews and meetings will be Telephone Only until further notice.  We are also asking our clients to mail all checks/contributions to be deposited into client accounts, instead of bringing them into our offices.

Please remember to:

  1. Make your checks payable to: NFS (National Financial Services)

  2. Include your Account # or Registration Name (ex: Jim’s IRA, Sally’s TOD, Harry’s Trust, Jim and Sally’s Joint, etc.)

  3. Include the Contribution Year (2019 or 2020)


Welcome to MainStreet Investment Group!  We are so glad you found your way to our site!


MainStreet Investment Group was founded on the principles of integrity, superior client service and a commitment to accountability.  Our mission is to create a level of service that exceeds our client’s expectations.

If you are retired or close to retirement, it may be beneficial to work with an advisor who has a definable risk management plan, an investment management process and a level of service that exceeds client expectations.  It may be time to look at your portfolio and examine your investment objectives and transition from wealth accumulation to preservation and income.

MainStreet Investment Group has two office locations:  Tomahawk, WI and Thiensville, WI.  Please browse our site, and feel free to call either Randy Plantenberg or Rich Nagel to schedule a complimentary consultation to see what makes our approach unique and to discover new possibilities for your investment portfolio and financial planning needs.


Randy Plantenberg is located in our Tomahawk, WI office; Randy can be reached at (715) 453-0722.

This location’s office hours are Monday through Friday, 8:00am to 4:00pm.


Rich Nagel is located in our Thiensville, WI office; Rich can be reached at (262) 478-3000.

This location's office hours are Monday through Friday, 8:30am to 4:00pm.




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