Investors severely punished Volkswagen when trading opened on Monday morning in Europe, driving the German automaker's stock price off a cliff. The steep decline comes after the US Environmental Protection Agency accused the company of evading federal clean air laws, and its CEO was forced to apologize. The rout wiped away nearly a quarter of the company's share value virtually overnight—about 15.4 billion euros ($17.4 billion), according to Bloomberg. As of Monday morning US time, the price had rebounded a bit.
On Friday, the EPA handed down a damning citation to VW outlining a plot that, while highly nefarious, is pretty impressive in its scope: According to the EPA, the company outfitted half a million diesel-powered cars sold in the United States with software called a "defeat device" that could detect when the car was being officially tested for toxic emissions. During the test, the cars' computers would apply extra pollution controls; for the rest of the time, when the cars were being driven on the road, smog-forming emissions were up to 40 times higher than the legal limit.
It's unclear how far up the chain of command the deception reached. On Sunday, VW CEO Martin Winterkorn said he was "deeply sorry" for breaking the public trust and ordered an internal investigation. That won't stop the ongoing US investigation, which could ultimately result in up to $18 billion in fines. Monday's stock plunge wiped out nearly that same amount.