John Thornton

John M. Thornton, CFA, is Senior Portfolio Manager at Stephens Investment Management Group (SIMG), based in Houston, Texas. As a key member of SIMG’s investment team, he contributes to the firm’s rigorous, team-based approach focused on U.S. small- and mid-cap growth equities, leveraging in-depth analysis to identify transformative catalysts and durable growth companies. Thornton has helped develop and manage high-conviction portfolios aimed at capturing long-term structural shifts in the market.

Before joining Stephens in 2004, Thornton was a Senior Analyst and previously an Analyst at AIM Investments (now Invesco), where his work concentrated on small and mid-cap growth investment products. At SIMG, he and his colleagues draw on decades of experience managing small- and mid-cap securities across various market environments, specializing in U.S. growth equities with a particular focus on sectors undergoing significant change and innovation.

Thornton holds an MBA from The University of Texas at Austin’s Red McCombs School of Business and a Bachelor of Engineering from Vanderbilt University. His expertise spans portfolio management, fundamental research, and sector specialization within U.S. growth equities, and he has been recognized for his disciplined investment process and longstanding commitment to client alignment through incentive-based ownership in the firm.