99.87% of VOO is in companies VTI also holds, and 90.32% of VTI is in companies VOO holds. 500 companies are in both.
Of VOO
99.87%
Of VTI
90.32%
In both
500
Same exposure
88.60%
VOO holds 503 companies and VTI holds 3,457.
The first two percentages are each fund's own published weight sitting in companies the other fund also holds, measured against that fund's own total rather than against 100, because published weights rarely sum to exactly 100 once cash and derivative rows are set aside. They differ whenever the funds are different sizes, and that difference is the useful part: a small fund can sit almost entirely inside a large one while being only a slice of it. "Same exposure" is a different measure, the sum over shared companies of the smaller of the two weights, which is how much of a portfolio built from either fund would be the identical thing.