The 30 professional singers in the chorus are members of the American Guild of Musical Artists, and their contract with the SFSO expired at the end of July. Since then, the union and the symphony have been negotiating issues such as compensation, health care, job security, and performance and rehearsal guarantees. With talks at an impasse, the chorus members said they would strike on October 13, affecting performances this week.

Instead, the chorus members and the Symphony begin mediation tomorrow, and the concerts, Benjamin Britten's Spring Symphony conducted by Robert Spano, and Emmanuel Ax playing Mozart's Piano Concerto No. 27, will be performed as planned.