I've used Yahoo! Finance to get historical price and dividend data in the past. A recent experience has made me question its accuracy and left me searching for a trusted, accurate source.
Here is a problem I am seeing with differences in the historical distributions (dividend) data from Yahoo! Finance as compared to Google Finance for the Vanguard Wellesley Fund's distributions in 2008, symbol VWIAX.
For Google Finance, setting the graph to show dividends in 2008 on this page: https://www.google.com/finance?q=vwiax it says it paid out $1.97 total in 2008: $0.78 on 12/16/08, $0.00 on 9/25/08, $0.62 on 6/26/08, and $0.57 on 3/27/08
For Yahoo! Finance, as reported here: http://finance.yahoo.com/q/hp?s=VWIAX&a=00&b=1&c=2008&d=02&e=3&f=2013&g=v it says it paid $3.217 total in 2008: $0.572 on 3/27/08, $0.624 on 6/26/08, $0.593 on 9/25/08, and $1.428 on 12/16/08.
These differences are huge, and each source shows at least one distribution that smells out of whack with reality: the $1.428 12/16/08 distribution at Yahoo! and the $0.00 distribution on 9/25/08 from Google.
I was unable to find this data on Vanguard's site. Maybe it is there but just not easy to discover.
Who can be trusted to provide accurate dividend data?
edit: I checked on MSN Money which showed a total amount for 2008 that differs from both Google and Yahoo!.