About Us

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Our Story

Longs Peak Advisory Services, LLC ("Longs Peak") was established to provide the investment management community with guidance, education, and support relating to GIPS compliance and investment performance measurement, analysis, and reporting. While a Partner at a large GIPS verification firm, our founder, Sean Gilligan, recognized that many of his clients lacked the resources necessary to become GIPS compliant and get through their GIPS verification in a timely manner.

With his entrepreneurial spirit and determination to help these firms, Sean started Longs Peak. Sean and his team have extensive experience helping firms navigate the GIPS standards and calculate investment performance. Having worked with hundreds of firms of varying sizes across North America, Europe, the Middle East, and Asia, Longs Peak's consultants understand the unique needs and challenges firms face and are available to share this knowledge and experience with your firm.

Our Team


Sean P. Gilligan, CFA, CPA, CIPM – Managing Partner

Sean is the firm’s lead investment performance and GIPS consultant. He has 18 years of experience in the investment industry, 12 of them focused on GIPS and investment performance. Prior to founding Longs Peak, Sean worked in a variety of roles including equity trading for a large investment management firm, managing the portfolio accounting and investment performance reporting department of a wealth management firm, and as a partner with a public accounting firm specialized in providing attestation services, such as GIPS verifications, to investment managers. Outside of work, Sean enjoys hiking, traveling, and spending time with his wife and four young children.

Cameron Payseno - Associate​

Cameron is a statistician that joined Longs Peak in 2018 after graduating from the University of Colorado, Boulder where he was an Evans Scholar and graduated with an Honors degree in Quantitative Economics. Previously, Cameron worked in data analytics at Sandia National Labs where he analyzed and prepared financial projections to improve the management of multi-million-dollar proprietary projects. Cameron is also a Level II Candidate for the CIPM. Beyond numbers and finance, Cameron is a sports fanatic and loves the Red Sox and Broncos. ​

Jack Hanna - Associate

Jack is a mathematician that joined Longs Peak in February 2019, after graduating from the University of Colorado, Boulder where he graduated Summa Cum Laude with a BS in Applied Mathematics and Finance. Previously he has worked as a Data Scientist for Arrow Electronics and as a Process Improvement Analyst at McKesson. Jack is an outdoorsman that loves snowboarding and enjoys climbing many of the 58 fourteeners (mountains above 14,000ft) that Colorado has to offer. In addition, Jack is a YoungLife leader in Boulder Valley


Jocelyn Mullis, CFA, CIPM - Partner

Jocelyn oversees our operations and is our quality and risk expert. She has 11 years of experience working in financial services. Jocelyn started her career with Ernst & Young where she provided international tax services for a number of the world’s largest banks and asset managers. During her time with Ernst & Young, Jocelyn was based in New York, Shanghai and Hong Kong. She has also worked in wealth management and has provided consulting services to business managers and owners to help them interpret or improve their operations. Jocelyn is a runner and loves hiking and spending time outside with her husband, four kids and boxer, Wilson.


Nate Matteson - Senior Associate

Nate is a consultant that joined Longs Peak in 2016. He graduated from the University of Northern Colorado with a BS in Finance. Prior to joining Longs Peak, Nate worked as a fund accountant at Alps, where he helped clients reconcile accounts, calculate daily NAVs and prepare financial statements. Nate has passed both levels of the CIPM and is waiting to complete his work experience before receiving the designation. Nate played college football and rugby and enjoys lifting weights, skiing and remodeling his house.

Brendan McGraw - Associate

Brendan is a finance guru that joined Longs Peak in June 2019. He graduated with distinction from the University of Colorado, Boulder with a BS in Business Administration with an emphasis in Finance. Previously, Brendan worked for Liberty Global where he analyzed and maintained a robust framework for reporting and evaluating performance. Brendan is an outdoorsman that enjoys backpacking and mountaineering in the great Colorado outdoors and enjoys spending time with his border collie, Moose.

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Investment Performance and GIPS Consulting

Are you interested in learning more about our consulting services? Talk to one of our GIPS consultants or performance experts today!