Poor punctuality and reliability combined with slow revenue growth led to the operator's financial performance being below expectation.
The walkout by the RMT union is the latest move in the long running row over the role of guards on trains
Rail services on some of the country's busiest routes will be hit by a wave of fresh strikes that will run from Friday to Monday.
Commuters have suffered a second day of travel disruption as rail workers on three networks continue to strike.
Commuters on three London rail networks are facing travel chaos as staff walk out for 48 hours, causing services to grind to a halt.