SAO PAULO (Reuters) – Brazil’s Embraer SA on Monday said it had begun an arbitration process against Boeing Co, after the U.S. planemaker abruptly canceled a $4.2 billion deal over the weekend that was years in the making.

Embraer shares fell as much as 16% in Sao Paulo to a more than 8-year low on news of the cancellation, suggesting investors had hoped until the last minute that the takeover agreement would not fall apart.

The sudden collapse, triggered by a deadline that Boeing refused to extend, drew an irate response from Embraer on Saturday.

But on Monday, when Embraer executives hosted a call with analysts, the angry rhetoric was largely absent. Embraer is in a delicate situation, having bet the future of the company on Boeing only to find itself now in isolation and without a Plan B, all while the coronavirus crisis ravages the travel industry.

Still, Embraer tried to reassure investors that it remains a solid company, although its CEO Francisco Gomes Neto acknowledged that 2020 will be a “tough” year and that 2021 “will be worse than we had thought.”

He added that Embraer has been able to find $1 billion in cash savings for 2020, and that it has not suffered any aircraft order cancellations due to the coronavirus crisis.

Gomes Neto declined to provide more details on the arbitration process and if it will be accompanied by a lawsuit in either a Brazilian or a U.S. court.

Embraer had hoped to sell 80% of its profitable commercial aviation unit to Boeing and benefit from the U.S. planemaker’s marketing power to scale up sales of its E2 regional jets, which have been lauded for their fuel efficiency even as sales have lagged. It would then use Boeing’s cash to wipe out all of its previous debt and pay a $1.6 billion dividend to shareholders.

Boeing, meanwhile, was aiming to compete more directly with Airbus in the regional jets segment.

BRAZIL AND CHINA

A former state-owned company, Embraer has a close relationship with the Brazilian government, which holds veto power over strategic decisions, while the company remains a top provider of military technology.

“Maybe we’ll begin new negotiations with a new company,” Brazil President Jair Bolsonaro told reporters on Monday. Bolsonaro, a former army captain, had supported and approved of the Boeing deal even as others in the military remained suspicious that Boeing’s involvement could affect Brazilian interests.

Gomes Neto did not rule out a potential new sale to a different company, but declined to comment further. He joined Embraer only a year ago and was not a part of the executive team that drew up the deal with Boeing.

Analysts have speculated that Chinese companies might be interested in buying Embraer’s commercial aviation unit. But Bolsonaro and his inner circle have repeatedly attacked China over the coronavirus crisis, blaming it for the spread of the disease and creating a very public diplomatic spat.

On Monday, UBS also suggested China may be interested in buying up Embraer’s commercial planes.

“We believe China still aspires to a global aerospace leadership position and, in our view, (Embraer) would bring both the talent for design and development,” it said in a client note.