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Meet Our Staff

As our client, you will have a team of highly qualified professionals working for you to provide you with the best coverage for you, your family, or your business.  Building a long-lasting relationship with our clients is our number one priority.

John Theune, Waupun Insurance Agent

John Theune

Partner, Personal and Commercial Lines

John has been in the insurance industry since 1990. John moved to Waupun in 1992 and has been with SIA Insurance Services since that time.

He specializes in both Personal and Commercial lines of business.

John is married to Ann and has three children – Olivia, Owen, and Celia. In his spare time he likes to golf, coach, and spend time with family.

Jonathon Venhuizen, ChFC, CLU, CPFA, CRPS

Partner, Financial Consultant

Jon has been with SIA since June 2007. His areas of expertise are retirement planning, income planning, investments, 401k plans (including prevailing wage 401k plans), and life, disability, and long-term care insurances. Jon works closely with Associated Builders and Contractors as an ABC Insurance Trust representative and a member of the Wisconsin chapter’s legislative committee.

Jon holds the designations of Chartered Financial Consultant® (ChFC®) and Chartered Life Underwriter® (CLU®), both from The American College, Certified Plan Fiduciary Advisor (CPFA®) from the National Association of Plan Advisors, and Chartered Retirement Plans Specialist® (CRPS®) from The College of Financial Planning. The ChFC® designation currently requires more courses than any other financial planning credential. The curriculum covers extensive education and application training in all aspects of financial planning, income taxation, investments, and estate and retirement planning.

Jon has been one of the top producers with Packerland Brokerage Services since 2015. He has achieved “Top 25” status in 2015-2019 and 2022. He was also named to the Packerland Brokerage Services “Ring of Excellence” in 2018. He was named the “Young Professional of the Year” for 2022 and “Future 5” award recipient from Envision Greater Fond du Lac. In 2023 Jon was named a Senior Market Sales President’s Club award winner for being one of the top insurance brokers in the company.

Jon currently sits on the Fond du Lac County Board of Supervisors, the Boards of Directors of Pillar & Vine Foster Care Agency, and the Waupun Kiwanis Club. Outside the office Jon enjoys traveling with his family, watching his kids’ activities, and spending time with friends. He is also an avid Wisconsin sports fan.

Jon and his wife, Kim, live in Waupun with their two children, Ryker and Jaina.


Securities and advisory services offered through Packerland Brokerage Services Inc., and unaffiliated entity. Member FINRA & SIPC.

Jordan Sterk

Partner, Home, Auto, and Health Insurance Specialist

Jordan is a dedicated insurance professional with a passion for helping individuals and families protect what matters most. With over a decade of experience in the insurance industry, he specializes in Medicare, Home, Auto, and Health Insurance.

Beyond his professional life, he finds immense joy in his role as a loving spouse and a proud parent of three wonderful children. As a dedicated family person, he cherishes the time spent with his kids. They constantly remind him of the importance of nurturing strong bonds and creating lasting memories. In addition to his family, he is an active member of the Waupun Lions Club, a community organization committed to making a positive impact. Through his involvement, he strives to contribute to the betterment of our community and the lives of those around us.

When he’s not working or engaging in community activities, you might find him on the golf course, enjoying a round of golf. It’s his way of unwinding and staying active while appreciating the beauty of nature.

He is dedicated to providing personalized insurance solutions that meet your unique needs. Whether you’re looking for comprehensive Medicare coverage, home and auto protection, or health insurance options, he is here to guide you through the process and ensure you have the peace of mind you deserve.

Matt Syens

Partner, Commercial Lines Consultant

Matt Syens started with SIA Insurance in 2016. He brings over 20 years of professional experience working in the best interest of business owners and families. Matt graduated from Calvin College with a Bachelor’s Degree in Business in 2001. He then started his career working for the Wisconsin Office of Commissioner of Insurance for 5 years and then transitioned closer to home to work in the banking industry.

Matt has his Property and Casualty insurance license from the State of Wisconsin. He focuses on commercial insurance products and solutions, and can also help with your personal lines products as well. Matt is a high energy insurance professional who is dedicated to taking care of his clients’ needs and ensuring they find the right coverage to protect their assets from unexpected losses.

Matt and his wife Annie live in Waupun with their two children. In his spare time, Matt likes to golf, cook, and attend sporting events. Matt is an avid Wisconsin sports fan. Matt also serves on multiple committees for Central Wisconsin Christian School.

Kyle Heuver

Partner, Health Insurance Specialist

Kyle Heuver joined the SIA staff in August 2017. His area of focus is in employer group benefits as well as Individual Health and Medicare Plans. Prior to being licensed as a Life and Health agent, Kyle worked for 20 years as an administrator and teacher at a private Christian school. His transition from administrator/teacher to insurance agent still allows him to build relationships with people and best serve their needs.

Kyle and his wife Karen are natives to the Cedar Grove/Oostburg, WI area and have two grown children and a tail-ender, Alaina. Kyle enjoys spending time with his family, working in his yard, playing golf, watching Wisconsin sports, and singing karaoke. He and Karen love catering to their 2 grandsons, Jack and Riggs. Kyle currently serves as a director on the Waupun Business Alliance and is an active member at his church where he has served in numerous capacities.

Kate Burk

Agent - Health Insurance Advisor

Kate Burk is an Individual and Medicare Health Plan Advisor, who has been with SIA Insurance Services since 2013. What Kate enjoys most about her job is being able to help individuals, families, and seniors to find health insurance plans to fit their medical needs and budget.

Prior to coming on board with SIA, Kate worked as a CSR for a health insurance carrier and acquired extensive experience with individual, medicare, and group medical plans.

To be closer to family, Kate relocated to Wisconsin after graduating from the University of South Florida. In her spare time Kate enjoys the outdoors, traveling; and spending time with family, friends, her husband Kevin and daughters Delaney and Erin.

Kim Venhuizen

Customer Service Representative

Kim Venhuizen has been with SIA Insurance since August 2017. Kim comes to SIA having 15 years working in non-profit and administrative roles. She is licensed in Property and Casualty Insurance, working as a Customer Service Rep for our office.

What Kim likes most about her role with SIA is the people, both assisting those she works with and the clients she serves.

While out of the office Kim enjoys spending time with her family, traveling and being involved in the community. Kim serves as Vice President of the Board of Directors of REACH Waupun and has close ties to The Union Youth Center.

Kim and her husband Jon live in Waupun with their two children, Ryker and Jaina.

Cheryl English

Securities & Group Benefits Client Service Representative; Human Resources Assistant

Cheryl brings to SIA Insurance Services over 30 years of experience working in the Insurance/Financial industry. Cheryl has maintained her Property & Casualty and Life & Health producer licenses since 1999 and is currently working on acquiring her Securities license. She graduated from Illinois State University with a Bachelor’s Degree.

She is a creative and results-oriented business leader. Cheryl prides herself on her commitment to high quality customer service and helping meet the individual needs of a diverse client base.

Cheryl moved to Waupun in 2016 to be in close-proximity to family. She has two married daughters and six beautiful grandchildren.

In her leisure time, Cheryl enjoys attending her grandchildren’s sporting events, traveling, cooking, yoga, hiking, and developing a clean and healthy lifestyle.

Hollie Ganz

Personal Lines Customer Service Representative

Hollie Ganz joined the SIA Insurance family in November 2014 after graduating from Dordt College with her Associates Degree. Hollie is licensed in Property & Casualty, working as a Customer Service Representative with the Personal Lines department. She dabbles in Commercial lines, helping and learning when she can. Hollie enjoys working with the clients, trying to find their best insurance rates.

Hollie grew up in Waupun and came back after college to be closer to family. Hollie and her husband Bruce live just outside of Waupun with their daughter, Maeve and dog, Nahla. When Hollie isn’t in the office, she enjoys spending time golfing, ice fishing, or just catching up with family and friends.

Trisha Kok

Trisha has been with SIA since September of 2021. She is licensed in Property and Casualty working as a Customer Service Rep in our office.

What she enjoys most about her job is the clients she interacts with and her co-workers.

Trisha grew up in the Fox Lake area and graduated from Beaver Dam High School. Trisha lives just outside of Waupun with her husband, Cory and children Brayden and Brielle. In her spare time, she enjoys spending time with her family and friends. She also manages the books for their lawn care and farming business.

Kayla Boersma

Personal Lines Customer Service Representative

Kayla joined SIA in November of 2023. She is the newest member of the team after transitioning from 10+ years in the auto industry. She is licensed in Property and Casualty working as a Customer Service Representative.

She has enjoyed getting to know her coworkers and clients and is looking forward to growing with the company.

Kayla grew up in Fond du Lac, attended college at UW-Milwaukee, and has lived in Waupun for the last 10 years with her husband, their 3 boys, and their dog, Ringo. Outside of SIA, you will find her reading books, drinking coffee, or hitting the links at the golf course!

Sara Oosterhouse

Personal Lines Customer Service Representative

Sara started with SIA Insurance in 2008, took a break to stay home full time with her boys from 2018-2022, and then came back to work part time. She is licensed in Property and Casualty and works with personal lines as a Customer Service Representative.
Sara enjoys helping and interacting with clients in the office as well as on the phone and also appreciates that the SIA staff are not only her co-workers but her friends.
Sara enjoys biking, reading, swimming and spending time with family. Sara and her husband Mike live in Randolph with their two boys, Isaiah and Noah.

Patricia Ellie, Waupun Insurance Agent

Patricia (Pat) Ellie

Individual Health Specialist

Patricia (Pat) Ellie has been with SIA since December 2008. She specializes in Health Insurance especially Medicare Supplements and Medicare Advantage Plans. Pat is also licensed for Life, Property, and Casualty. Pat enjoys meeting her prospective clients and getting to know them on a personal level.

In her spare time Pat likes to fish, camp and garden (flowers and vegetables). She grew up in Central Wisconsin and moved to Milwaukee as a child. Pat is married to Dale Ellie and recently moved to Waupun after living in the Green Lake area for nearly 20 years. Pat and Dale have two married children and two grandchildren.

Dan Zeratsky, Waupun Insurance Agent

Dan Zeratsky

Personal and Business Lines Specialist

Dan has been with SIA since November 2007. He handles Commercial and Personal Lines.

What he enjoys most about his job is the interaction with good people and the chance to help protect their assets.

In his spare time, Dan enjoys outdoor activities. He is also involved in youth sports programs in the Fox Valley Area.

Dan grew up in Green Bay, WI. He is married to Deborah and has 2 children.

Mike Lassila

Agent, All Lines of Coverage

After graduating from UW-Milwaukee with a dual-option BBA, Mike joined Wausau Insurance as an Employee Benefits Consultant in 1977 out of their Kansas City Office. He then became a Regional Sales Manager for the Ohio Casualty Group and was named “Man of the Year” in 1983. Mike joined SIA in 1991 and handles all lines of insurance out of SIA’s Jackson office.

Mike has a keen appreciation of the required skill-set of small business owners after many years of insuring them.

Away from the office, Mike and his wife, Patty, enjoy spending time with their three children. Something you might not know about Mike is that he thinks of himself as a “Yooper” and has family which lives on Lake Superior shores.