Robert Lynch, the chief executive of embattled Lumber Liquidators of Toano, quit suddenly Thursday, sending stock shares tumbling again.

The flooring firm is still reeling from a report in March on CBS “60 Minutes” program that laminate flooring from China contained high levels of dangerous formaldehyde.

The once robust firm has seen its value decline more than two-thirds since February. Stocks plunged further after Lynch’s resignation.

He will be replaced temporarily by Thomas Sullivan, the company’s founder, until a new CEO can be found. The firm’s chief financial officer, Daniel Terrell, has announced that he’s leaving his post in June.

Lumber Liquidators at first tried to reassure customers and regulators that its flooring was safe, but then announced it was halting all sales of its Chinese laminate flooring.

The firm also was affected by stock traders who were profiting by selling its shares short.