I am trying to calculate the annual growth rate for a short sale. I've
entered the first amount as a positive number (because it was cash coming in)
and the second amount as a negative number (because it was cash going out).
When I use XIRR I get a negative percentage as the annualized return.

As a simple example, if I enter 110 on the first date and -100 a year later
XIRR gives me negative 9.1% as the annualized return. Since I have 10 more
at the end of the year, it seems that my return must be positive.

Am I misinterpreting this result or what?

Thanks for your help.