It was VTSMX, but it's closed to new investors and they're encouraging people to convert to VTSAX ever since they lowered the minimum investment of Admiral class shares to the $3000 that investor class shares were. That was the only advantage of investor class shares since they were more expensive. If you don't have the $3000 minimum you could invest in a target date fund which have a $1000 minimum, or the ETF version of VTSAX (VTI) which has a minimum equal to the value of one share.