Boeing’s West Coast factory workers have gone on strike after rejecting a contract offer, disrupting the production of the 737 MAX and causing Boeing’s shares to drop by over 2%.

The strike, involving around 30,000 International Association of Machinists and Aerospace Workers, marks the first since 2008.

Workers overwhelmingly rejected the deal, which offered a 25% pay increase over four years, far short of the 40% demand.

Boeing’s stock has already lost 38% this year amid mounting issues, including safety concerns and leadership changes.