Pay for FTSE 100 bosses fell to a five-year low last year and could drop further as firms bow to investor anger over bumper pension payouts.

Median total pay for bosses of the UK’s largest listed firms stood at £3.4m in 2018, compared with £4m a year earlier, according to Deloitte. It is the lowest level since 2014, when UK rules first required companies to report a single figure for chief executive pay. That year, median pay packages totalled £4.4m.

The report found that the median increase in base salary for FTSE 100 bosses stayed at only 2%, while nearly a third received no pay rise at all. Bonus payouts remained at similar levels of about 70% of the maximum allowed under each company’s pay criteria. Median base salaries reached £868,600 while bonus payments – excluding long-term incentives – averaged £1m.

However, a notable shift has taken place for pay in lieu of pensions – cash sums of up to 50% of basic salary given to top bosses in lieu of pension contributions – with about one third of FTSE 100 companies cutting pension pay for new executive hires.

Companies are grappling with new guidelines meant to bring these cash payments to top executives into line with other staff. The Investment Association, which manages £7.7tn in assets of 250 members, has shamed firms for failing to cut payments to less than 25% of existing director’s base pay as a first step.

Stephen Cahill, a vice-chairman at Deloitte, said: “We have seen many companies come forward as ‘first movers’ in response to new regulatory changes, with 29 companies reducing pensions for new hires.

“Without a doubt, executive pensions have been the hottest topic of 2019 and we expect this to continue, with a growing focus on incumbent executives receiving the highest pension rates.”

Companies that have fallen foul of those guidelines over the past year include the travel firm Tui, the banking giant Standard Chartered, the supermarket chain Sainsbury’s and the drinks company Diageo.

The Lloyds Banking Group boss António Horta-Osório has been a lightning rod for criticism over excessive payouts and was summoned before MPs earlier this year for pocketing an extra £419,000 cash in lieu of pension, an additional payment of 33% of his £1.3m basic salary. Lloyds’ ordinary staff receive employer pension contributions of only 13%.

Deloitte said median pay for FTSE 100 chiefs has also been depressed by rules that bar CEOs from cashing in shares until long after they have left the company.

If the two trends continue, it could mean pay for FTSE 100 bosses dropping yet again.

Cahill said: “In the coming year we expect to see a further shift in reduced pensions and requirements for executives to hold shares post-leaving.

“Given current uncertainty in the UK business environment, shareholder pressure and regulatory controls should be balanced with the need to ensure that the UK is able to attract the calibre of talent that can deliver continued prosperity for businesses.”