Derry-based Seagate Technology axed around 300 staff last year as part of world-wide global restructuring plans.
The US-owned tech giant is one of the biggest employers in the North West.
Almost 100 jobs were previously believed to be at risk at the factory in Springtown.
However, company accounts show the headcount was reduced by almost 300 at the Derry operation.
A strategic report filed by Seagate Technology (Ireland) said the company had been forced to cut its workforce “dramatically” in response to tougher economic conditions.
Opened 31 years ago, the factory produces a tiny specialised part for hard drives called a recording head.
Workers recently voted to secure trade union recognition for the first time over fears of job cuts.
According to company accounts for the year ending 30 June 2023, the company said it “reduced its headcount by approximately 300 people with the restructuring substantially completed by the end of the first quarter of 2024 financial year”.
It stated that the cost of this restructuring plan was about $17.2m (£14.1m).
On Friday, a spokeswoman for Seagate told BBC NI that the content of the strategic report reflected the company’s restructuring in Northern Ireland.
She said Seagate committed to a restructuring plan in April 2023 to “reduce its cost structure to better align operational needs to current economic conditions, while continuing to support the long-term business strategy”.
The spokeswoman added: “As a result, since 30 June 2023, the company reduced headcount by approximately 300 through a voluntary process which completed in September 2023.”
