Market value added
The excess of the actual or theoretical market value of a firm over its book value.
Using a simplified example, for an all-equity financed firm with an actual or theoretical market capitalisation of $130m and book value of equity $100m:
MVA = $130m - $100m
In practice a number of adjustments would be made both to the market values and to the book values used in the calculation of the MVA.
So in practice the assessment of MVA is both more complicated, and arguably more subjective, than the simple calculation illustrated above.