Frontier Airlines and Spirit Airlines, two prominent U.S. budget carriers, announced Monday that they had agreed to merge.

The airlines, which together offer 1,000 daily flights serving destinations in the United States, the Caribbean and Latin America, said in a statement they would achieve $1 billion in annual savings from combining, without layoffs. They also said they expected to add 10,000 direct jobs by 2026 and create thousands more through their business partners.

They said the merger was expected to close in the second half of the year, subject to regulatory review and approval of Spirit shareholders. Frontier’s parent company, Frontier Group Holdings, in which the private equity company Indigo Partners has a controlling interest, has approved the deal.

Under the merger agreement, Frontier equity holders would control 51.5 percent of the combined company, and Frontier would name seven of 12 board members. The board would be headed by William A. Franke, the chairman of Frontier and the managing partner of Indigo Partners. The companies said branding would be decided before the merger closes.

The combined operation would have annual revenue of approximately $5.3 billion based on 2021 results, the announcement said.