Shares in $4.9 billion waste management operator Cleanaway plunged close to 13 per cent on Thursday after the surprise departure of chief executive Vik Bansal.

The company's shares hit a low of $2.27, a drop of 12.7 per cent on Wednesday's closing price, after the company confirmed in a statement to the ASX that chairman Mark Chellew would step into the executive chairman role while it searched for a new chief executive.

The company said Mr Bansal had reflected on his future priorities over the Christmas and New Year period and decided it was the right time for the exit. "The board and Mr Bansal mutually agreed it is the right time for Cleanaway to move forward under new leadership."

In an internal memo seen by The Sydney Morning Herald and The Age, Mr Bansal told staff it would be "business as usual" despite his departure. He said the demands of his role, which included commuting from Sydney to Melbourne weekly, had been difficult.