Deutsche Lufthansa cut its guidance for the year, warning that it will be increasingly challenging for its flagship airline to break even as it contends with negative market trends and aircraft-delivery delays.

The company, which includes the likes of Eurowings, Austrian Airlines and Brussels Airlines, said it now expects adjusted earnings before interest and taxes for 2024 between 1.4 billion euros and 1.8 billion euros ($1.52 billion-$1.96 billion). It had previously guided for adjusted EBIT around EUR2.2 billion.

The company said its new outlook was largely dependent on the performance of Lufthansa Airlines and the fourth-quarter performance of Lufthansa Cargo.

The change in guidance comes as the company said its earnings have been hit by a so-called market-related decline in yields in all traffic regions, but particularly in Asia.

“Lufthansa Airlines is particularly affected by the challenges posed by the negative market trend and by inefficiencies in the flight operations of Lufth-ansa and Cityline, also due to delayed aircraft delivery,” the company said, adding that it is launching a comprehensive turnaround program in order to redress the airline.

Second-half earnings at its other passenger airlines as well as at Lufthansa Technik and Lufthansa Cargo were expected to be broadly at their prior-year level, or in some cases higher, the group said.

Citing preliminary figures, the airline said it made EUR686 million in group 2Q adjusted EBIT, down from EUR1.1 billion a year ago.

Meanwhile, Lufthansa Airlines made EUR213 million in 2Q adjusted earnings before interest and taxes in the second quarter. For the first half, it swung to a EUR427 million adjusted EBIT loss.

Lufthansa said it would provide further details about its financial outlook later this month when it publishes its quarterly result.

Write to Pierre Bertrand at  pierre.bertrand@wsj.com