Feb 21 (Reuters) - AbbVie is looking to sell at least $13 billion of corporate bonds to help fund its acquisitions of ImmunoGen and Cerevel Therapeutics, Bloomberg News reported on Wednesday, citing people with knowledge of the matter.

The sale is expected to be announced as soon as Thursday, following fixed-income investor calls on Wednesday, the sources said, requesting anonymity as the discussions were private, according to the report.

The size of the offering is subject to change and will be determined on the day of the sale.

AbbVie did not immediately respond to Reuters' request for a comment.

In December, AbbVie announced back-to-back acquisitions - a $8.7 billion plan to buy Cerevel and its $10.1 billion deal for ImmunoGen, which was recently completed.

AbbVie has since said that it plans to focus on smaller deals to support its growth through the next decade.

On Tuesday, the drugmaker named Robert Michael to replace Richard Gonzalez as CEO in July.

(Reporting by Sriparna Roy and Bhanvi Satija in Bengaluru; Editing by Sherry Jacob-Phillips)