Show us the Transactions!

Both Google Finance and Yahoo! Finance can record one's portfolio transactions.

Both also graph share prices with markers for events such as dividends and splits; even news items in Google's case.

Why don't they also show events that are relevant to the individual investor? Like when one has bought or sold shares?

A green dot for buys, a red dot for sells, and voilà: one instantly gets an idea how good one's market timing is.

C'mon Google. C'mon Yahoo!. You already have the data, now show us the transactions!