Shares of U.S. automakers Ford Motor and General Motors slipped about 1% each in morning trade on Monday after the United Auto Workers (UAW) union warned of more walkouts unless a new labor deal is reached.

UAW President Shawn Fain said on Friday that the automakers had converged on a 23% wage hike, but told members there was "more to be won".

Though Fain signaled a deal may be close, some analysts expressed worries about the financial impact of the demands on the automakers.

"The economics continue to get worse with reported further concessions on pension, both higher 401K contributions and increased benefits for retirees," said Wells Fargo analyst Colin Langan.

"Possibly a sign a deal could be done soon. However, most of the update was concerning as Fain interprets increased offers as a sign there is more to get," he said.

The UAW wants workers at EV battery plants to be covered by union contracts, and defined benefit pensions restored for all workers. It had opened bargaining with a 40% wage-hike demand.

The union and General Dynamics also reached a tentative agreement over a new labor contract covering hundreds of workers at some of the U.S. defense contractor's facilities, the company said on Monday.

The strikes and the negotiations with the UAW have weighed on automakers' shares. Since the contract talks began in mid-July, U.S.-listed shares of Stellantis have marginally risen, while Ford and GM shares were down at about 23% and nearly 27%, respectively.

Ford and GM trade at a 11.34 and 4.14 times forward profit estimate, respectively, which is well below the S&P 500's about 19.15 multiple.

(Reporting by Nathan Gomes in Bengaluru; Editing by Pooja Desai)