Boeing's deliveries plummeted again in August due to the prolonged grounding of the 737 MAX following two deadly crashes

Boeing experienced another big drop in plane deliveries in August, the company reported Tuesday, as the months-long grounding of the 737 MAX continues to hit the aerospace giant.

Boeing delivered just 18 planes last month, down nearly 72 percent from the year-ago period, according to data on Boeing's website. Plane deliveries are closely watched by Wall Street because they are tied to revenue.

The company's financial outlook remains murky due to the 737 MAX, which was grounded in mid-March following two crashes which killed 346 people.

Boeing has been working on fixes to address concerns by the Federal Aviation Administration and other global regulators. The company has said it expects the aircraft to return to service early in the , while acknowledging the timeframe is dependent on regulators.

For the year so far, Boeing has delivered 276 planes, down 42.6 percent from year-ago deliveries through the end of August and well below the 500 delivered by arch-rival Airbus through the first eight months of 2019.

Airbus has delivered 207 of the A320neo, a rival to the 737 MAX.

Boeing's net orders for 2019 are negative 85, due in part to a hit from Jet Airways, whose planes were grounded after the company ran out of cash.