For one of my mutual funds, Yahoo and google does not give complete historic data. I have instead, grabbed the monthly prices for the fund from my bank statements going back about 9 nine years. I entered these under the proper file name for the mutual fund in the QUOTES folder.
It is working for most months, but in some months, it comes back with a calculation that \i have lost 100% of my investment in one month and gained it all back in the next month (give or take a few dollars0 IS there a specific date each month that PS looks for to complete it's calculations for monthly gain? Do I have to ensure I have a value for the last day of each month?