Fractional leadership. Infinite potential.
ABOUT US
Harmonic Sum helps ambitious brands unlock exponential growth
through strategic leadership,
collaborative thinking,
and targeted inputs
to do more than simply add value.
We change the equation.
KATE FOSTER LENGYEL
FOUNDER. CEO. OPERATOR. STRATEGIC ADVISOR.
Kate is an entrepreneur and consumer brand executive with more than 20 years of experience building, scaling, and transforming businesses at every stage.
Kate has:
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launched brands from scratch
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repositioned legacy businesses
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had her startup acquired
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raised capital
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built high-performing teams
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secured world-class retail partnerships
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guided organizations through rapid growth
She understands what ambitious brands need because she's built them herself.
SERVICES
Specializing in beauty, fashion, and media,
offering strategic leadership for every phase of growth.
How We Partner
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Fractional CEO & Founder Leadership
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Strategic Advisory
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Board Advisory
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Entrepreneur in Residence
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Executive Mentorship
Areas of Expertise
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Brand Strategy & Positioning
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Commercialization & Go-to-Market
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Growth Strategy
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Organizational Design
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Fundraising Strategy
WHO WE WORK WITH
Founder-Led
Companies
Venture-Backed
Businesses
P.E. Portfolios
Established Brands in Transformation
RECENT ENGAGEMENTS
A GLOBAL BIOTECH COMPANY commercializing a breakthrough consumer innovation | An ICONIC LINGERIE BRAND repositioning the business and building the next chapter | A CULT-FAVORITE FRAGRANCE BRAND developing the brand and fundraising strategy required to scale | A successful DERMATOLOGIST-FOUNDED SKINCARE BRAND sharpening its positioning, product story, and growth strategy | An EMERGING MEDIA PLATFORM defining its business model and path to market | A EUROPEAN WELLNESS COMPANY preparing for entry into the highly competitive U.S. market | A FAMILY ENTERTAINMENT & MEDIA PLATFORM refining its product-market-fit and GTM | A VENTURE-BACKED BEAUTY COMPANY strengthening its commercialization, investor narrative, and go-to-market plan | A PRESTIGIOUS UNIVERSITY launching an innovation institute
