Perpetual Guardian — Auckland's 100:80:100 Four-Day Week Trial

Perpetual Guardian, a New Zealand trust, wills and estate-administration company based in Auckland, ran an eight-week trial in March–April 2018 in which around 240 staff worked four days a week for the same five-day pay, under a '100:80:100' model (100% pay, 80% of the time, 100% of the output). The trial was independently monitored by Dr Helen Delaney of the University of Auckland Business School and Professor Jarrod Haar of Auckland University of Technology, using pre- and post-trial staff surveys.
The AUT-published evaluation found self-reported stress levels fell by roughly 7–15%, the share of staff who felt they could effectively manage their work-life balance rose from 54% before the trial to 78% after it, and team engagement scores rose 20–40% to levels the researchers described as among the highest recorded in a New Zealand workplace survey (AUT, 2018).
On the strength of these results, Perpetual Guardian's board made the four-day week permanent company policy from 1 November 2018 — one of the first such commitments by a private employer anywhere — and the trial became the reference case cited by 4 Day Week Global and by the later government-run and multi-employer trials in Iceland, Belgium and Portugal.
The evidence has real limits: it covers a single, self-selected professional-services employer over only eight weeks, relies substantially on self-reported survey measures rather than independent output audits, and larger multi-company trials run elsewhere since have shown more mixed productivity results across different sectors.

Read the full analysis: https://news.aut.ac.nz/__data/assets/pdf_file/0019/188002/Final-Perpetual-Guardian-report_Professor-Jarrod-Haar_July-2018.pdf