This paper proposes an indicator for detecting business cycle turning points involving mixed frequency business survey unbalanced data. It is based on a hidden Markov-switching model and allows for the detection of regime changes in a given economy where information is displayed monthly and/or quarterly. Starting from Gregoir and Lenglart (2000) we propose an adaptable framework which can be applied to many situations involving monthly, bimonthly and quarterly data. The proposed methodology is applied to the French economy. Using balances from business survey, this indicator measures the probability of being in an accelerating or a decelerating phase referring to the output growth rate cycle. The index is confronted over the past with a ref...