<human>: Can you provide a brief overview of the text?

I recently received some money via check that I wanted to invest in some Vanguard mutual funds. I deposited the check into my Ally bank account and setup a new Vanguard account choosing three funds and setting their initial amounts to pull from my Ally account. Vanguard says they first have to verify I own the bank account by depositing and withdrawing 2 small charges, the amounts of which I will give to them. No problem, this is pretty standard. However, later that day I realized, duh, I had forgotten that, because of its size, my check will take 5 days to process at Ally! Again, no problem, I'll just hold off on verifying the account with Vanguard until the funds are available. Then, today, I get a get text from Mint telling me that my bank account had been overdrawen. Yep, I checked, without my even logging into their site to verify my bank account, Vanguard had withdrawn the money anyways. I'm actually not sure what will happen now, Vanguard shows each fund purchase, but Ally only shows the first two, I did not have enough money in the account for the third purchase without the check. However, honestly that part doesn't worry me too much, I'm sure I'll have to pay a few fees, but Ally has been reasonable to me about simular timing issues before. What really bothers me is that Vanguard withdrew the money without me ever proving it was actually my bank! That suggests I could just give them anybody's account number and wait a few days and they'd withdraw money for me. Scary. 

Anybody else have somthing like this happen to them?
<bot>: Vanguard was supposed to use two small deposits to verify my bank account before pulling my money. They didn't wait for me to verify the deposits. Due to poor timing on my part I over drafted my account.