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Our History & People

Our History

Mainsail was established by Les Gosule, Bob Jesson and Jim Oslin in 1999 as a way to serve the growing financial planning needs of their CPA firm, Gosule, Butkus & Jesson, LLP in Milton, Massachusetts. Over the last 10 years Mainsail began building a relationship with David Alexander of Alexander Advisors in Harvard, Massachusetts through their wealth management study group and mutual partnership with 1st Global, a resource partner to the CPA-centric wealth management industry.

In 2017, the two financial planning firms became Mainsail Advisor Group, LLC. The firm’s ability to formally share expertise and coordinate services represents an evolution and growth in becoming a premier provider of tax-efficient wealth management services to eastern Massachusetts through the advancements in technology and resources provided through Avantax.

Our People

Les C. Gosule* CPA, PFS, CVA, MST

Financial Advisor


As a business owner for over 30 years, Les has devoted his career to understanding the challenges of small and medium-sized business owners. This is illustrated by continually improving his skills and increasing the breadth of service offerings his firm provides.

Les received his bachelor's degree in business administration from Bentley College in 1969 and became a CPA in 1972. In the years following he earned his Masters of Science in Taxation from Northeastern University, the Personal Financial Specialist (PFS) designation and Certified Valuation Analyst (CVA) in 1995 and became an Investment Advisor Representative in 2001.

In addition to being a CPA, Les is a General Securities Representative and Investment Advisor Representative with his series 6, 7, 22, 63, 65 registrations and is licensed to offer various insurance solutions. He holds the Personal Financial Specialist (PFS) designation.

He’s spent considerable amounts of free time to teaching at Northeastern University, and is a devoted volunteer in many philanthropic and civic organizations.

David Alexander* CPA/PFS, MST, CFP®

Financial Advisor


David is an owner in Mainsail Advisor Group, LLC, and leads the firm’s office in Harvard, Massachusetts along with his support staff. Prior to joining Les and Robert Jesson at Mainsail, David is the founder of Alexander Advisors, an accounting and financial advisory firm providing tax, business consulting and wealth management services to a diverse group of clients for over 30 years.

David received his Bachelor of Science degree in Accountancy from Bentley College in 1982, his Master of Science degree in Taxation from Bentley in 1989, and became a CPA in 1986.

In addition to being a CPA, he is a Personal Financial Specialist (PFS) and CERTIFIED FINANCIAL PLANNER™ professional. David is a General Securities Broker and Investment Advisor Representative with his Series 7, Series 66, and is licensed to offer various insurance solutions.

David is a member of the American Institute of Certified Public Accountants, Massachusetts Society of Certified Public Accountants and is active in several community events and boards.

Insurance services offered through 1st Global Insurance Services, Inc.

Michael P. Kiziuk

Financial Advisor

Michael has over 20 years of experience in the wealth management industry, with a background in investment research, trading, and financial planning. He works with the Mainsail team to provide tailored investment solutions and an exceptional client service experience. His extensive investment background is an ideal match with the firm’s tax partners to achieve Mainsail’s mission: Integrated Tax and Financial Planning.

Michael received his degree in Finance from the Villanova University School of Business. He is a General Securities Agent and Investment Advisor Representative, holding the FINRA Series 7, 63 and 66 registrations, and is licensed to offer insurance products.

Outside of the financial world, Michael coaches youth sports on the South Shore and enjoys spending time with his wife and four children.

Robert M. Jesson, CPA, MST

Bob is a founding partner in the CPA firm Butkus & Jesson since 1983, and a consultant in Mainsail Advisor Group, LLC since 2001.

Since his career began, Bob has taken a personal interest in his clients. Additionally, he is an advocate for small and medium-sized businesses and is known for bringing a common sense approach to solving complex tax and operational problems.

Bob’s professional education is a testament to his work ethic and commitment to furthering his knowledge in business and taxation. He received his business administration degree in 1980 from Bentley College.

He then earned a Master of Science in taxation in 1985, and Advanced Professional Certification in taxation in 1990.

He earned both of these degrees while attending night school and working full-time in his chosen field.

Cindy Coupal

Wealth Management Coordinator


Cindy is a Wealth Management Coordinator at Mainsail Advisor Group, LLC, and supports David in the firm’s Harvard Office. She joined the firm in 2012, bringing over 30 years of business experience to the practice. Her responsibilities at the firm include guiding the wealth management operations including marketing, client services, establishing and maintaining client accounts and information systems, internal reporting, and is a liaison between Avantax and our clients.

Cindy plays a key role in supporting our wealth management professionals. She conducts research into client requests, manages the timely transfer of critical information and documentation, and provides other services for clients.

Cindy holds a Bachelor of Science degree in Business Management from Fitchburg University. She is a lifelong resident of Massachusetts recently moved to Florida. She enjoys spending time with her family.

Stacey Tuvey

Wealth Management Coordinator


Stacey is our newest Wealth Management Assistant at Mainsail Advisor Group, LLC and supports Les and Mike at the firm’s office in Milton, Massachusetts.

Stacey brings with her years of advanced administrative, organizational, and interpersonal skills. She is focused on customer service with excellent oral and written communication ensuring dependable quality and confidentiality. Her responsibilities include, but are not limited to, liaison with the firm’s clients, home office and numerous financial service companies; the establishment and maintenance of accounts, ensuring the integrity of asset transfers, marketing activities, etc.

Stacey was born and raised in Massachusetts and moved to New Jersey for some years to be near family. She is an alumna of “Up with People” in 1986. She has relocated back to Massachusetts in 2020 to settle down and spend more quality time with her loved ones.

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