what is "model instability" in Quant/regression?

is it something concerning standard error? I know there is alway parameter instability for regression, but whant about model instability? I can’t find the definition in book, can anyone help me with this?

I think model stability is mostly an issue for financial data because of its dynamic nature

I did a question in Quant/Regression about “model instability” last week. Can’t find it now… I remembered the answer talked about something like standard error instability? epoh Wrote: ------------------------------------------------------- > I think model stability is mostly an issue for > financial data because of its dynamic nature