Barnaby Wiener is an investment officer and equity portfolio manager and the head of sustainability and stewardship for MFS Investment Management® (MFS®).

He manages the firm's Prudent Wealth, Prudent Capital and Prudent Investor strategies and serves as a portfolio manager on the firm's Managed Wealth strategy, an alternative strategy run by a committee of the firm's portfolio managers. He is also responsible for continuing to integrate sustainability across our investment platform. He is based in London.

Barnaby joined the firm as a research analyst in 1998. He assumed portfolio management duties in 2003 and took on the head of sustainability and stewardship role in 2020. He also served as director of European research from 2003 to 2010.

Prior to joining the firm, he was an equity research analyst at both Merrill Lynch and Crédit Lyonnais. Before that, he served as a captain in the British Army. Barnaby is a graduate of Ampleforth College and Oxford University.