This paper considers why organizations use promotions, rather than just monetary bonuses, to motivate employees even though this may conflict with efficient assignment of employees to jobs. When performance is unverifiable, use of promotion reduces the incentive for managers to be affected by influence activities that would blunt the effectiveness of monetary bonuses. When employees are risk neutral, use of promotion for incentives need not distort assignments. When they are risk averse, it may—sufficient conditions for this are given. The distortion may be either to promote more employees than is efficient (the Peter Principle effect) or fewer. “Promotions serve two roles in an organization. First, they help assign people to the roles where they can best contribute to the organization's performance. Second, promotions serve as incentives and rewards.” (Milgrom and Roberts (1992, p. 364)) “Promotions are used as the primary incentive device in most organizations, including corporations, partnerships, and universities … This … is puzzling to us because promotion-based incentive schemes have many disadvantages and few advantages relative to bonus-based incentive schemes.” (Baker, Jensen and Murphy (1988, p. 600))

It is widely thought that incomes risks can be shared by trading in financial assets. But financial assets typically carry some risk idiosyncratic to them, hence, disposing incomes risk using financial assets will involve buying into the inherent idiosyncratic risk. However, standard theory argues that diversification would reduce the inconvenience of idiosyncratic risk to arbitrarily low levels. This paper shows that this argument is not robust: ambiguity aversion can exacerbate the tension between the two kinds of risks to the point that classes of agents may not want to trade some financial assets. Thus, theoretically, the effect of ambiguity aversion on financial markets is to make the risk sharing opportunities offered by financial markets less complete than it would be otherwise.

We propose regression‐based tests for mean‐variance spanning in the case where investors face market frictions such as short sales constraints and transaction costs. We test whether U.S. investors can extend their efficient set by investing in emerging markets when accounting for such frictions. For the period after the major liberalizations in the emerging markets, we find strong evidence for diversification benefits when market frictions are excluded, but this evidence disappears when investors face short sales constraints or small transaction costs. Although simulations suggest that there is a possible small‐sample bias, this bias appears to be too small to affect our conclusions.