mass retirement
Often refers to the large-scale retirement of Japanese baby boomers (団塊の世代) around 2007–2009, but can be used for any large wave of retirements.
The mass retirement of the baby boomer generation had a major impact on companies.
Labor shortages are becoming more serious due to mass retirements.
早期退職 means early retirement (often voluntary), while 大量退職 emphasizes the large number of people retiring at once.
定年退職 is mandatory retirement at the set age, whereas 大量退職 focuses on the scale of the retirement wave.
Compound of 大量 (large quantity) and 退職 (retirement).