German drugmaker Merck KGaA is reportedly considering the sale of its generics unit to help fund its purchase of Swiss biotech Serono.

Citing unnamed sources within the company, German newspaper Handelsblatt said that the group may have already been given the go-ahead by its board to divest the division, and estimated that the move could add around 4 billion euros to its coiffers.

A spokeswoman for Merck declined to comment on the report, but already the rumour had spurred an increase of almost 3% in the company’s share price in early-morning trading, reflecting positive investor sentiment over the potential sale of the division.

Merck agreed to buy the Bertarelli family's 64.5% controlling stake in Serono for 1,100 Swiss francs per share in September last year, in a deal worth 10.6 billion euros ($13.5 billion) which is widely expected to close this month.

Once completed, the firm’s branded drugs business will be combined with Serono to create Merck-Serono Biopharmaceuticals, which will have its headquarters in Geneva, and its US base in Boston. The new group will have pro forma sales of around 7.7 billion euros.