(Reuters) -Institutional Shareholder Services has recommended Pfizer ( PFE ) investors reject a proposal on executive compensation due to changes made in the long-term awards for CEO Albert Bourla and other top executives.

The proxy adviser said on Wednesday that the changes added about $1 million in additional value for CEO.

The modification "significantly undermines the at-risk nature of the awards and a pay-for-performance philosophy," the firm said.

Pfizer ( PFE ) did not immediately respond to a request for comment.

The company's shareholders are expected to vote on the proposal at the annual meeting scheduled for April 24.

(Reporting by Bhanvi Satija in Bengaluru; Editing by Anil D'Silva and Sriraj Kalluvila)