Alert based on a document over time

Hello,

We'd like to have alerts based on the evolution of the data of a specific document over time.

Here is our use case:
Every day we index documents which represent financial instruments with their metrics (e.g. volatility). Therefore every day an instrument has a new version of its data and we represent this version through a 'timestamp' field. The id of the document is made of the instrument's id and the version.

Now we would like to have alerts that would tell us when an instrument's metric has reached a threshold. E.g. alert us when the difference between today and 10 days ago of an instrument's volatility is more than 20%.

So far we have been able to build alerts on top of multi-documents aggregations (e.g. the average volatility of the instruments of type 'bond'), but is it possible to have alerts for a single document?

Thanks for your help.