Mr McNulty is on a two-year rolling contract paying pounds 398,000 a year, meaning he could be in line for a payout of up to pounds 800,000.
Shandwick has put aside pounds 2.5m to pay off Mr McNulty, Colin Trusler, the former head of the group's British business, and a number of regional managers and administration staff who will also lose their jobs.
The changes have been prompted by increasing pressure from shareholders, lead by the UK Active Value Fund, which have become increasingly concerned about the group's ailing share price.
Shandwick said it was still in takeover talks with several rivals and expected an outcome, one way or another, within the next few weeks.
Pre-tax profits were flat at pounds 9m (pounds 9.2m) due to a disappointing performance from the UK division. Shares rose 1p to 53.5p.Reuse content