The action comes after an external review uncovered the facts behind a coding error in Axa Rosenberg's risk modelling and led to co-founder Barr Rosenberg's resignation.
"The Axa board has determined that the group's founder, Barr Rosenberg, and head of research, Thomas Mead, did not act in accordance with the firm's escalation policy and code of ethics," S&P said.
"Specifically, the external review concluded that both acted to limit dissemination of information regarding the error.
"Axa also confirmed that global chief investment officer Agustin Sevilla did not act in a manner that was consistent with the firm's escalation policy."
Mead will assist in the transition of his role to co-founder Kenneth Reid in the coming months, while Sevilla will step down and move into a senior researcher role.
S&P put the Axa Wholesale Global Equity and Axa Generation Rosenberg Global Equity Core funds on hold in April, when it was first told of the coding error and the decision to conduct a review.
"Although Rosenberg will be available to the group for consultation, we believe the changes and departure are likely to result in a drain on the group's intellectual property," S&P said.
