…for most country X year observations in the Piketty and Zucman (2013) [data], aggregate Tobin’s q is less than 1—the book value of wealth exceeds the market value. …if corporate market equity value is lower than properly measured book equity value, it may be that assets are less valuable in corporate hands—due, perhaps, to poor shareholder control. (Piketty and Zucman (2013) discuss this hypothesis, which seems plausible in light of the cross-country pattern in Tobin’s q.)

– Matthew Rognlie, in “A note on Piketty and diminishing returns to capital” June 15, 2014, which I discuss and link to in “The Wrong Side of Cobb-Douglas: Matt Rognlie’s Smackdown of Thomas Piketty Gains Traction.” Piketty and Zucman (2013) can be found here