Can a firm have a negative turnover during a period of time? Can a firm have a negative turnover during a period of time? I'm asking this because I couldn't find any details on the web.

I am working with a data table that holds a lot of firms and their turnovers for each month. Some of them have negative turnover for one or more of the months.

Is that possible? How does a negative turnover work? How does it appear in the first place?
One possible circumstance relates to firms undertaking long term contracts (eg for building or engineering work). Where a contract is uncompleted at the end of a period, the firm may (depending on its accounting policies) include in its turnover an amount reflecting its assessment of the work in progress.  Sometimes unforeseen difficulties in completing a contract will subsequently come to light, and it may become necessary to include an offsetting reduction within turnover for the next period. If the contract is a large proportion of the firm's activity, then this could result in overall turnover for that period being negative.