Shares of McDonald’s Corp. MCD, -3.16% sank 3.0% in morning trading Tuesday, which put it on track to suffer the biggest one-day decline this year. The stock’s price decline of $6.46 is shaving about 44 points off the Dow Jones Industrial Average’s price DJIA, -0.22%, which is down about 3 points. The fast-food behemoth’s stock, which is headed for the biggest percentage decline since it fell 3.1% on Dec. 20, 2018, has now shed 4.2% in two sessions, and sits 4.7% below its Aug. 9 record close of $221.15. The selloff comes as shares of rival burger chain Wendy’s Co. WEN, -12.00%, which closed at a record as recently as Thursday, tumbled 12.5% after the company said it will make a $20 million investment to take another shot at serving breakfast nationwide. MKM Partners Brian Bittner said he wondered that given there are over 6,000 Wendy’s restaurants, he wondered what implication this could have on the entire quick-service category, specifically McDonald’s and Burger King. Shares of Burger King parent Restaurant Brands International Inc. QSR, -1.95%, which closed at a record high on Aug. 29, slumped 2.3% on Tuesday.