The development comes after the TUC called for a move towards a four-day working week, citing research that found almost half of workers were behind the idea. It said UK workers put in the longest hours in the EU, behind only Austria and Greece.
A recent study by Oxford University economists found that a four-day working week would boost productivity.
Wellcome, the world’s second-biggest research donor after the Bill and Melinda Gates Foundation, has been monitoring the success of New Zealand insurance company Perpetual Guardian, which last year switched to a four-day working week.
Mr Whiting told the Guardian: “It looks like moving the working week to four days rather than five gets you a broader productivity and wellbeing benefit.
“You have a healthier workforce, a reduction in sickness absence and improved sense of work-life balance.”
He said analysis of the impact of Perpetual Guardian’s switch in March and April, which involved 240 staff, showed small increases in total output, despite staff working shorter hours.
Wellcome said it was still gathering evidence and would make a final decision in the coming months. It noted that one potential risk could be a loss of flexibility if people are required to work only Monday to Thursday.