NEW YORK — According to published reports, KKR & Co. has formally approached Walgreens Boots Alliance about a deal to take the company private, in what could be the biggest-ever leveraged buyout.

The New York-based private equity firm has been preparing a proposal to potentially buy out shareholders of Walgreens Boots, said the people, who asked not to be identified because discussions are private. It’s unclear how feasible the transaction would be, given the need for large amounts of financing, and Walgreens Boots and KKR could decide against pursuing a deal, the people said.