A couple of years ago, I inherited some money, which I put in a Vanguard brokerage account. It's 100% in VTSAX because at the time I didn't understand the difference between VTSAX and VTI. I do not and will never add money to this brokerage account - it was a one-time lump sum worth about $300k now. All of my ongoing contributions go into a tax-advantaged account elsewhere.
I'd like to know if I can change it all from VTSAX to VTI without having to sell the entire $300k and pay capital gains tax on it. Is this possible? I can't ask Vanguard because any such questions are met with "We do not give tax advice."
Also, same question, but what if I convert the VTSAX to VT?