Norway's Subsea 7 has spent around $8.6m on its own shares.
The OSV owner said it entered into an agreement to acquire 616,434 shares from an employee benefit trust.
The stock is currently trading at NOK 115.60 ($14).
Following the deal, the number of its own shares it holds in treasury is 857,887, representing 0.26% of the equity.
There are now no more shares in employee trusts.
