$Boeing(BA.US)$'s newest model twin-aisle jet -- the 777X -- probably won't be in service until 2025, Barron's has learned, pushing the timeline for first deliveries back 12 to 24 months later than previously expected.

News of the delay pushed shares of the planemaker down more than the overall market on Monday. Boeing stock (ticker: BA) was off 1%, while the S&P 500 and Dow Jones Industrial Average were down 0.5% and 0.6%, respectively. Reuters reported the setback to the 777X program Friday, citing a source briefed on the matter.

Boeing has amassed roughly 375 orders for the 777X. Twin-aisle jets don't sell at the same volume as single-aisle jets, but they are more expensive. A 777X lists for roughly $425 million while a Boeing 737 MAX 8 single-aisle jet lists for about $120 million. (List prices don't always represent what an airline pays.)

Boeing said late last year that the first 777X jets would be delivered to customers in late 2023. Delays could be a result of U.S. aviation regulators increasing their scrutiny of any new plane following two deadly 737 MAX crashes in 2018 and 2019.

While the 777X's delay has hurt Boeing stock, investors will likely turn their focus to Boeing's ability to ramp up MAX production and return to positive cash flow.

Boeing is scheduled to report first-quarter earnings Wednesday morning. Wall Street is looking for a 25-cent-per-share loss from about $16 billion in sales. Analysts also expect Boeing to have burned through about $2.9 billion in free cash flow. However, analysts expect free cash flow to be positive, coming in at $2 billion for 2022. Boeing has burned through about $28 billion total in the past three years.

Coming into Monday trading, Boeing stock was off about 12% year to date.