Shares of Boeing Co. /zigman2/quotes/208579720/composite BA -0.68% took another dive Thursday, and accounted for the bulk of the Dow Jones Industrial Average's /zigman2/quotes/210598065/realtime DJIA -0.09% decline, after Southwest Airlines Co. /zigman2/quotes/201071949/composite LUV -0.97% pushed out its expected return of the grounded 737 Max fleet to January. Boeing's stock dropped 3.5% in morning trading, after losing 3.1% on Wednesday after second-quarter results. The stock has now shed 7.5% amid a four-session losing streak. The $12.51 price decline on Thursday was shaving about 85 points off the Dow's price, which was down 126 points. Southwest said it will expand the 737 Max-related flight adjustments through Jan. 5, 2020, while American Airlines Group Inc. /zigman2/quotes/209207041/composite AAL -2.96% said Thursday it was staying at Nov. 2. Separately, Boeing Chief Executive Dennis Muilenburg said the company will consider temporarily shutting down 737 Max production if its return is delayed beyond the current October forecast.