Hynes joined Wellington after graduating from Wellesley College in 1991 with a BA in economics and has spent her career at the firm. She worked as a global industry analyst covering pharmaceutical and biotechnology companies, led the health care sector research team and, from 2013 to 2024, was a portfolio manager on the firm's Health Care Team, including the Vanguard Health Care Fund.
Since 2014 she has been one of Wellington's three managing partners, who share responsibility for governing the partnership. She became chief executive in July 2021, the fifth CEO since Wellington became a private partnership and the first woman in the role; the firm's Form ADV lists her as chief executive officer and president from that month. She is a CFA charterholder.
In June 2026 Wellington agreed to acquire Hartford Funds from The Hartford, folding it into Wellington's US wealth business under the Wellington brand.