Core Insights - Heartland Advisors reported a strong performance for small-cap stocks in Q3 2025, with the Russell 2000® Index increasing by 12.39%, outperforming the S&P 500 Index's 8.12% rise [1] - The Heartland Value Plus Fund achieved an 8.51% return in Q3 2025, lagging behind the Russell 2000® Value Index, which gained 12.60% [1] Company Highlights - Materion Corporation (NYSE:MTRN) was identified as the top performer for the Heartland Value Plus Fund in Q3 2025, being a vertically integrated producer of advanced engineered materials [3] - Materion Corporation's stock experienced a one-month return of 3.07% and a 52-week gain of 11.67%, closing at $118.10 per share on October 10, 2025, with a market capitalization of $2.448 billion [2] - The company specializes in high-performance materials based on beryllium, which is lighter than aluminum and significantly stiffer than steel [3] Hedge Fund Interest - Materion Corporation was held by 24 hedge fund portfolios at the end of Q2 2025, an increase from 22 in the previous quarter, indicating growing interest among institutional investors [4]