Shares of Boeing Co. /zigman2/quotes/208579720/composite BA -0.68% fell 2.3% in afternoon trading Monday, enough to be the biggest drag on the Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA -0.09% , as worries over the fallout from the grounding of the aerospace giant's 737 Max aircraft continue. The stock was both the biggest percentage and price decliner in the Dow, with its $8.20 price decline shaving about 56 points off the Dow's price. The Dow as up just 39 points, paring earlier gains of as much as 291 points. J.P. Morgan analyst Seth Seifman lowered his 2019 earnings estimate for Boeing, as he pushed out his expectations for resumption of 737 Max deliveries to December from October following the new Federal Aviation Administration requirement to make additional flight-control software changes . Seifman cut his 2019 adjusted EPS estimate to $13.23 from $15.43 (FactSet consensus is $14.85) and his revenue forecast to $86.10 billion from $92.02 billion (FactSet consensus $100.13 billion). "The new modification means that [Boeing] faces heightened risk around timing, since more delays could ultimately force another production cut," Seifman wrote in a note to clients. Boeing's stock has now shed 9.1% over the past three months while the Dow has gained 1.5%.