Heinz has defended a proposed “golden parachute” payout to current CEO Bill Johnson if he were to leave the company after its planned $28bn acquisition by a group of investors let by Warren Buffett.

If Johnson were to exit the ketchup maker following its takeover by investment funds Berkshire Hathaway and 3G Capital, he would be entitled to a $56m “golden parachute”, Heinz revealed in a regulatory filing. In addition, Johnson controls shares worth almost $100m, while his vested deferred compensation is worth approximately $57m.

A spokesperson for Heinz defended the size of the payout, insisting that Johnson’s success in generating shareholder value since he took the helm of the group in 1996 justified the severance package.

“The payments reflect Mr. Johnson’s success in creating billions of dollars in shareholder value over his successful 15-year tenure as president and CEO,” the spokesperson said. “His success includes delivering total shareholder returns of 177% since 2006 and the 19% premium to Heinz’s all-time high share price that all Heinz shareholders will receive in the merger.”

The spokesperson also emphasised that a majority of the potential payout had been agreed prior to the takeover proposal. “This compensation consists of equity that Mr. Johnson accumulated over his 30-year career with Heinz and existing equity awards and contractual rights that were in place well before the announcement of the proposed merger.”

However, the proposed merger faces an ongoing US Securities and Exchange investigation over trading prior to the takeover proposal was announced and some on Wall Street have suggested the deal undervalues Heinz. In light of these concerns, the size of Johnson’s payout could draw into question his ability to act as an impartial representative of shareholder interests.

In the regulatory filing, Heinz was quick to emphasise that Johnson acted properly when the takeover proposal was raised, providing a list of meetings and discussions between Johnson and representatives of Berkshire and 3G. The group also outlined the strategic rationale for the merger, reiterating “the Heinz board’s belief that the $72.50 per share merger consideration exceeds Heinz’s likely value as a standalone company, including its potential for future growth”.