SageForum for UK versions of Sage 50- Help and support.

Is there any option in sage 50 cloud to make stock negative?

Yes

Allow negative stock is in settings>company preferences

could you please explain me, how it will impact on my reports and other tables?

It allows the qty in stock to go negative.

Which report are you concerned about?

The stock level on the stock table will become negative when you sell more than you have.
The sold items will not have cost prices so will assume the current cost price.

After allowing negative stock, there is a warning showing when I enter zero cost item in my invoice.
Your profitability report will be impacting. So, what will be the impact?

Profitability reports calculate the profit on transactions by taking the cost price away form the sales price.

If items cost you nothing to buy, then the profit is going to be wrong.

This is not a result of negative stock it is a result of an item with zero cost.

Product has sales price and cost price both zero.
If I am making invoice for this product then it will impact on my Profitability report?

If you buy something for nothing and sell it for nothing then there is no profit so it will not affect profitability.

I suggest you run profitability, enter the transaction and then rerun profitability to check this for yourself.

I guess if you are looking at average sale profitability then it will have an impact as you have a sale with no profit but then anything would have an impact on that.