Farre-Mensa stopped short of saying these differences put public companies at a longer-term disadvantage, but the findings touch on the trade-offs involved with being a public vs. private company.

FORBES: Public Companies Out-invested By Private Firms

Privately held firms also account for about 54.5 percent of spending on plants and equipment, professors John Asker and Alexander Ljungqvist of NYU and Joan Farre-Mensa of Harvard estimated in a recent study comparing private- and public-company investments.

FORBES: Private companies pull economy along