Germany's Siemens Energy wants to buy the remaining shares in its Spanish wind power subsidiary Siemens Gamesa for €18.05 ($19.06) per share, it said on Saturday.
The offer is the equivalent of around 4 billion euros.
Siemens Energy aready owns 67.1% of the company. If successful, Siemens Energy would take its struggling wind power subsidiary off the stock market and integrate it into the group.
The move was not unexpected, after the company, which is listed on the MDax, announced that management was considering a cash offer to take the subsidiary off the stock market in a statement several days ago.
Rumours about a possible takeover have been circulating for months. Siemens Gamesa's figures have been disappointing for the past four quarters as the unit struggles with costs and production problems.
In a statement earlier this month, Christian Bruch, chief executive of Siemens Energy, said Gamesa's results had been "disappointing" and were "weighing heavily" on the parent firm.
Siemens Energy had sought to improve the situation, by moving some of its managers to leading posts at the subsidiary, including Jochen Eickholt, who has led Gamesa since March.