09:51 AM EDT, 10/24/2024 (MT Newswires) -- Boeing ( BA ) shares were falling on Thursday as its factory workers rejected a new labor contract, fueling concerns that the ongoing strike that started in September could extend into next month.

Frontline Boeing workers voted 64% against the most recent offer, according to a late Wednesday statement from the International Association of Machinists and Aerospace Workers, which represents about 33,000 members at the troubled plane maker.

The offer included a 35% general wage increase over a four-year period, up from the 25% hike proposed in the original offer in September. The deal included improved terms to workers' ratification bonuses and enhanced contributions by Boeing ( BA ) to retirement plans, among other benefits.

"After 10 years of sacrifices, we still have ground to make up, and we're hopeful to do so by resuming negotiations promptly," Jon Holden, president of IAM district 751, and Brandon Bryant, president of IAM district W24, said in the joint statement. "Ten years of holding workers back unfortunately cannot be undone quickly or easily, but we will continue to negotiate in good faith until we have made gains that workers feel adequately make up for what the company took from them in the past."

The entire union supports the decision of districts 751 and W24, IAM International President Brian Bryant said. The union said it plans to "immediately" share new dates for further negotiations with Boeing ( BA ).

Boeing ( BA ) declined to comment on the vote. Its shares were down 2.1% in Thursday trade.

The development deals a fresh blow to the company, which reported a wider-than-expected third-quarter loss on Wednesday amid the ongoing strike. Earlier this month, Boeing ( BA ) disclosed plans to lay off about 10% of its workforce in the coming months.

"We have some really big rocks that we need to get behind us to move the company forward. The first and foremost on everybody's mind today is ending the IAM strike," Boeing ( BA ) Chief Executive Kelly Ortberg, who took over the helm in August, said on a Wednesday conference call. "We've been feverishly working to find a solution that works for the company and meets our employees' needs."

Truist Securities flagged the possibility of the strike extending into November.

"The strike has now been ongoing for 41 days, with the implications for the broader supply chain only worsening over time," Truist said in a Thursday note. "We now expect that the strike has the potential to persist into November, which will negatively impact aircraft production volumes in (the fourth quarter of 2024) and (the first quarter of 2025) and likely means that Boeing's ( BA ) plan to get the MAX back up to a rate of 38/month will slide deeper into 2025."

Boeing ( BA ) Chief Financial Officer Brian West told analysts on the Wednesday call that the company's production plans for the 737 program will be impacted due to the strike. "We had been making good progress on stabilizing production and preparing for 38 per month by year-end, but those objectives will now take longer due to the IAM work stoppage," West said at the time.

Price: 153.78, Change: -3.28, Percent Change: -2.09