The about face comes as the board grapples with the activist's efforts, and just days before Starboard's Jeff Smith was slated to meet with the CEO, sources said.

Former Pfizer CEO Ian Read and ex-CFO Frank D'Amelio said they will not be involved with activist investor Starboard Value, which reportedly wants the U.S. drug giant to make changes to turn its performance around.

Former Pfizer Inc. executives Ian Read and Frank D’Amelio have decided “not to be involved” in Starboard Value’s activist campaign against the drug company, according to statement released on their behalf late Wednesday.