Leader of Impact Stavros Siokos ’98PhD: “Do Well by Doing Good”

Stavros Siokos ‘93MS, ‘98PhD, spent part of his career at Salomon Brothers in the 1990s and served as managing director at Citigroup—but he really found his calling in finance when he co-founded London-based Astarte Capital Partners in 2015 to invest in sustainable real estate assets and natural resources (or natural capital) around the world.

“You change lives, you change communities,” he said. “In the financial world, you make money by evaluating the work of others. It’s very rare that you do the work yourself. But here, you’re getting your hands dirty, your boots dirty. You see real life.”

Siokos, who will be honored Oct. 22, 2026, at the Isenberg School of Management’s Leaders of Impact event at the Museum of Fine Arts in Boston, earned a master’s degree in electrical and computer engineering and a PhD in operations research, both from UMass Amherst. He has 30 years of experience across capital markets, asset management, and alternative investments. Astarte Capital Partners manages institutional capital from 45 countries and has been recognized for its approach to natural-capital investing. 

Investing for Financial, Environmental, and Social Impact

Through the firm, Siokos has helped demonstrate how investment can be used not only to generate financial returns but also to create long-term environmental and social impact. One example is Astarte’s sustainable forestry work in Paraguay, where degraded pastureland is being transformed through responsibly managed forests, conservation efforts, and large-scale carbon capture.

The award-winning forestry project has received international recognition for its contribution to sustainable investment and natural capital. During United Nations General Assembly Week in New York City in September 2026, Siokos was invited to present the project at several countries’ missions to the United Nations, including those of the United Arab Emirates and Paraguay. The engagements provided an opportunity to showcase the project and its role in mobilizing institutional capital for sustainable development.

“Through our investments in sustainable forestry in Paraguay and regenerative agriculture, we see first-hand how long-term institutional capital can support economic growth while strengthening local communities and delivering environmental benefits,” said Siokos. “Mobilizing more capital toward these opportunities will be increasingly important as investors seek to combine long-term financial performance with exposure to the transition toward more sustainable and resilient economies.”

In a column published July 27, 2026, by Agri Investor, he identified four factors that are critical to successful investment: land with secure title, access to water, efficient logistics infrastructure, and a strong legal framework. Paraguay, Siokos explained, offers all four. The country also provides conditions that allow trees to grow quickly: Trees in Paraguay can grow as much as a meter per month, with approximately six years between planting and harvest, he said. 

But Siokos said the project’s significance goes beyond forestry productivity.

“The forestry project is probably the most impactful one,” he said. “Astarte is at the forefront of sustainable natural capital investment in Paraguay; it is a legacy project for me. The project is helping create employment opportunities for local residents, including women, while supporting conservation and the return of wildlife to protected areas. It’s a large-scale effort that brings together economic development, environmental stewardship, and social impact.”

An Enduring Isenberg Connection

Siokos has maintained close ties to Isenberg and UMass Amherst throughout his career. In 2019, he spoke to Isenberg students and UMass INFORMS Student Chapter members about investing in private markets to generate social and environmental benefits. He discussed several Astarte investments, including the forestry initiative in Paraguay and projects in East Africa, as well as investments in education.

His former PhD advisor, Anna Nagurney, PhD, the Eugene M. Isenberg Chair in Integrative Studies, professor of operations and information management, said it has been meaningful to watch Siokos’ career evolve and his influence grow.

“It has been truly special to have had Stavros as one of my PhD students and to see over the years the outstanding impact he has had, along with his team at Astarte Capital Partners,” she said. 

Nagurney noted that Siokos’ work in forestry and agriculture reflects the intersection of finance and some of the world’s most pressing challenges.

“I continue to be amazed by the profound positive impact he has had on our world and continues to make through his investments in forestry and agriculture that address such critical societal issues as climate change, food security, and many resource challenges in global supply chains, while at the same time, yielding positive financial returns,” she said.

Nagurney and Siokos co-authored the book Financial Networks: Statistics and Dynamics, published by Springer.

“I’m also so proud of the work that we did together, including co-authoring the book,” she said. 

Nagurney described Siokos as not only a global thought leader and colleague but also as friend.

“He is incredibly generous, thoughtful, and kind,” she said, noting that their professional connection has continued over the years. Siokos remains a center associate of the Virtual Center for Supernetworks at UMass Amherst and is scheduled to speak at its 25th anniversary symposium in November. 

Siokos, in turn, credits Nagurney with having a lasting impact on his life and career.

“Anna has been a huge influence in my life,” he said. “She gave me the ability to do things that I didn’t think was possible. Being a co-author with her of a book takes you to a different level.”

Leader of Impact Award

Siokos said being recognized at Leaders of Impact—which celebrates leaders who make a difference in their organizations, industries, and communities in innovative and tangible ways—is significant because he hopes to show Isenberg students that it is possible to “do well by doing good.”

“Receiving this award is important to me,” said Siokos. “I always wanted to create something with an impact in the financial world—for the next generation to see that you can make serious money by doing something good, you don’t have to be a shark. You can be something more meaningful, and the current young generation seems to care more about that. You can touch lives globally and can make it in a system that is a win-win for everyone.”