Altes Capital appoints Jonathan Siegel as Managing Partner of Altes Ascent
New York, NY — January 19, 2026 — Altes Capital today announced that Jonathan Siegel has joined the firm as a Partner, serving as Managing Partner of Altes Ascent, the firm’s impact investing division.
In this role, Siegel will be responsible for overseeing Altes Ascent’s strategy and investment activities, with a focus on market-rate opportunities that seek to align financial fundamentals with long-term impact across infrastructure, energy, and the broader real economy.
“Jonathan brings a combination of investment discipline, strategic judgment, and experience applying capital-markets discipline to complex real-economy systems,” said Brian Altenburg, Managing Partner at Altes Capital. “He shares our view that a long-term orientation and disciplined approach are important in addressing structural challenges across these sectors.”
Siegel brings extensive experience in investment and capital markets, with an increasing focus on impact-aligned strategies, real-economy systems, and collaborative capital formation. He has worked with founders, operators, institutional investors, and long-term partners through strategy development, capital-markets insight, and sustained engagement.
“At its core, Altes Ascent reflects a view that long-term value creation and real-world impact can be aligned when approached thoughtfully and with discipline,” said Siegel. “I look forward to working with the Altes team and engaging with partners across the ecosystem as the platform continues to develop.”
Altes Ascent operates as Altes Capital’s dedicated impact investing division and evaluates opportunities across sectors central to economic resilience. Investment strategies are pursued in accordance with Altes Capital’s established investment processes and governance framework.
