I have two drop down boxes from a list, year and month. These are used to
calculate expiration dates for various option contracts on stocks and
futures. I have had no problem writing the formulas for the easy ones (-:.
Here is where i am stumped

rules
expiration is the 3rd business day prior to the 25th of the month, if the 3
day prior to the 25th is NOT a business day, then it is the first business
day prior to that

for example if the 22nd falls on a Sunday, the third business day prior
would be Friday the 20th, if that Friday was a holiday, the formula would
have to pick up Thursday