Rather than reveal my account value, let's say it holds $10,000 and I'll divide all the actual amounts by the same multiple.
I started with $4200 one year ago.
In March 2020, I added $580 near the market bottom.
So as of March 2020, I had $4780 in the account.
Vanguard's "account" menu has a "personal performance" option near the middle of the lists. I selected "retirement account" only, and it shows a personal rate of return of 37%.
But my current balance shows as $10,000, or more than double the account value after adding money in March. So I would expect 100% return or more, annualized.
$10,000 / $4780 = 2.09x, or a 109% return.
Any ideas on what Vanguard is doing for it's calculation?