CHICAGO (AP) – Chicago Symphony Orchestra musicians say they are on strike after contract talks broke down.

They say in a news release that picket lines will form starting at 8 a.m. Monday. They say management is still trying to reduce their pension benefits after nearly a year of negotiations.

The musicians walked out after completing a Sunday afternoon concert and negotiating all evening.

Steve Lester, bassist and chair of the musicians’ negotiating committee, says they “have been clear from the beginning that we will not accept a contract that diminishes the well-being of members or imperils the future of the orchestra.”

The contract expired Sept. 17, 2018, and was extended to March 10.

Helen Zell, Chicago Symphony Orchestra Association board chair, says trustees are disappointed but still “look forward to the eventual resolution to a new contract.”