(Reuters) – Walgreens Boots Alliance Inc (WBA.O) has been exploring whether to go private following private equity interest in the U.S drug store chain, according to people familiar with the matter.

In recent months, Walgreens has held preliminary discussions with some of the world’s largest private equity firms about putting together what would be the biggest ever leveraged buyout, the sources said.

Walgreens has tasked investment bank Evercore Partners Inc (EVR.N) with exploring whether a deal can be put together, the sources said, cautioning that a deal is far from certain.

The sources asked not to be identified because the matter is confidential. Walgreens declined to comment, while Evercore did not immediately respond to a request for comment.