Filter Month End From Daily Data

I have a series of daily data and I am looking to filter for month end business days and create a sum.

This piece of code gets what I need, arbitrarily, for the 7th day of every month. How can I amend the code so that rather than 7, I have the last business day of every month?

select FROM_DATE, PORTFOLIO, SUM(VALUES) from MyTable
where DATEPART(day,FROM_DATE) = 7
group by FROM_DATE, PORTFOLIO

I have the following code for last business day of month (from a previous question raised on these forums), but when I set DATEPART(day,FROM_DATE) equal to the following piece of code, I get no results.

CASE DATEDIFF(dd,0,DATEADD(mm,DATEDIFF(mm, 0, FROM_DATE),-1))%7
WHEN 5 THEN DATEADD(dd, -1, DATEADD(mm,DATEDIFF(mm, 0, FROM_DATE),-1)) -- if Saturday subtract one day
WHEN 6 THEN DATEADD(dd, -2, DATEADD(mm,DATEDIFF(mm, 0, FROM_DATE),-1)) -- if Sunday subtract two days
ELSE DATEADD(mm,DATEDIFF(mm, 0, FROM_DATE),-1)
END