Hi all -- I'm hoping for help understanding what my 401(k) is invested in. Done through Fidelity, it's described as Vanguard Institutional 500 Index Trust, with a disclaimer explicitly stating "This investment is not a mutual fund," but looking up "trust funds" doesn't exactly yield the info I'm looking for.

The symbol is 87267D106 which delivers Google results for VINIX, so am I invested in an account that's investing in VINIX?

I explicitly chose the fund due to its low costs, and then I received a notice late last year that the fund was converting into something else, and I have been confused since. My main goal is that I'm receiving regular dividends and understand what my investment is, so thank you for any help!