From Longman Business Dictionary
reversalre·vers·al /rɪˈvɜːsəl-ɜːr-/ noun1[countableC] a change to an opposite arrangement, process, or course of actionreversal ofThe move was a reversal of Kodak’s previous policy.
reversal inMoney managers predict a reversal in the industry’s rising share values.
2[countableC] a failure or other problem that prevents you from being able to do what you wantIn spite of setbacks and reversals, his business was at last making money.