All the alleged key causes of SOE [State-Owned Enterprise] inefficiency—the principal-agent problem, the free-rider problem and the soft budget constraint—are, while real, not unique to state-owned enterprises. Large private-sector firms with dispersed ownership also suffer from the principal-agent problem and the free-rider problem. So, in these two areas, forms of ownership do matter, but the critical divide is not between state and private ownership—it is between concentrated and dispersed ownerships.

Ch. 5: 'Man exploits man; Private enterprise good, public enterprise bad?', The pitfalls of privatization, p. 116 - Bad Samaritans: The Myth of Free Trade and the Secret History of Capitalism (2008)