Opportunities lost in a period

Opportunities lost in a period

Hi,

I am trying to create a report where I can extract all opportunities lost during a month. Is there a field that logs this info ?
I tried to extract  opps lost with closing date within a specivifc month, but it did not work ´cause I can´t be sure that it wasn´t actualliy closed within the month informed in the closing date field.

regards,

Benno.