A new meta-field of “forensic economics” has begun to emerge, uncovering evidence of hidden behavior in a variety of domains. Examples include teachers cheating on exams, road builders skimping on materials, violations of U.N. sanctions, unnecessary heart surgeries, and racial biases in employment decisions, traffic stops, auto retailing, and even sports judging. In each case, part of the contribution of economic analysis is in uncovering evidence of wrongdoing. Although research questions differ, forensic economic work shares commonalities in approaches and limitations. This article seeks to draw out the common threads, with the hope of stimulating further research across fields. (JEL K13)

A major component of the Mutual Fund scandals of 2003 was the allegation that certain investors were allowed to engage in the late trading of mutual fund shares. Under the forward pricing rule, trades in U.S.-based open-ended mutual funds are required to be priced at the next net asset value per share (NAV) calculated after an order is received. 1 For funds that calculate NAVs once per day at 4 PM Eastern time (the vast majority), orders received before 4 PM should be priced at the NAV calculated on the day of the trade while trades received after 4 PM should instead be priced at the next-day net asset value. 2 Late trading occurs when investors place trades after 4 PM but still receive the 4 PM price. Late traders can use information revealed after 4 PM to guide their trades: buying fund shares when their current value is greater than NAV and selling when the reverse is true. Doing so allows them to earn expected abnormal returns at the expense of the fund’s long-term shareholders. 3

The level of diseconomies of scale in asset management has important implications for tests of manager skill and the expected level of performance persistence. To identify the causal impact of fund size on future returns, we exploit the fact that small differences in returns can cause discrete changes in Morningstar ratings that, in turn, generate discrete differences in fund size. Using our regression discontinuity approach, we find that ratings significantly increase fund size, but that fund size has a negligible effect on fund returns. Within Berk and Green’s (2004) model, the absence of meaningful fund-level diseconomies of scale implies that the lack of performance persistence arises from a lack of fund manager skill. Alternatively, the lack of performance persistence may arise from competitive pressures outside of their model.

Despite the popularity of prediction, markets among economists, businesses, and policymakers have been slow to adopt them in decision-making. Most studies of prediction markets outside the lab are from public markets with large trading populations. Corporate prediction markets face additional issues, such as thinness, weak incentives, limited entry, and the potential for traders with biases or ulterior motives—raising questions about how well these markets will perform. We examine data from prediction markets run by Google, Ford Motor Company, and an anonymous basic materials conglomerate (Firm X). Despite theoretically adverse conditions, we find these markets are relatively efficient, and improve upon the forecasts of experts at all three firms by as much as a 25% reduction in mean-squared error. The most notable inefficiency is an optimism bias in the markets at Google. The inefficiencies that do exist generally become smaller over time. More experienced traders and those with higher past performance trade against the identified inefficiencies, suggesting that the markets' efficiency improves because traders gain experience and less skilled traders exit the market.

We use mutual fund recommendations to test whether editorial content is independent from advertisers’ influence in the financial media. We find that major personal finance magazines (Money, Kiplinger’s Personal Finance, and SmartMoney) are more likely to recommend funds from families that have advertised within their pages in the past, controlling for fund characteristics like expenses, past returns and the overall levels of advertising. We find little evidence of a similar relationship for mentions in the New York Times or Wall Street Journal. Positive media mentions in both newspapers and magazines are associated with significant future inflows into the fund while advertising expenditures are not. Therefore, if we interpret our coefficients causally, a large share of the benefit of advertising in our sample of personal finance magazines comes via the apparent content bias. The welfare implications of this apparent bias are unclear, however, since our tests suggest that bias does not directly lead publications to recommend funds with significantly lower future returns than they might have recommended in the absence of any bias. In selecting funds to recommend, magazines overweight past returns relative to expenses, and as a group their recommendations do not outperform even an equal- weighted average of their peers. Nevertheless, this approach leaves magazines with large numbers of funds with high past returns from which to select, and so bias towards advertisers can be accommodated without significantly reducing readers’ future returns. Interestingly, the recommendations of Consumer Reports, which does not accept advertising, have future returns comparable to or below those of the publications which accept do advertising.

The independence of editorial content from advertisers' influence is a cornerstone of journalistic ethics. We test whether this independence is observed in practice. We find that mutual fund recommendations are correlated with past advertising in three personal finance publications but not in two national newspapers. Our tests control for numerous fund characteristics, total advertising expenditures, and past mentions. While positive mentions significantly increase fund inflows, they do not successfully predict returns. Future returns are similar for the funds we predict would have been mentioned in the absence of bias, suggesting that the cost of advertising bias to readers is small.

We study the choice between named and anonymous mutual fund managers. We argue that fund families weigh the benefits of naming managers against the cost associated with their increased future bargaining power. Named managers receive more media mentions, have greater inflows, and suffer less return diversion due to within family cross-subsidization, but departures of named managers reduce net flows. Naming managers became less common between 1993 and 2004. This was especially true in the asset classes and cities most affected by the hedge fund boom, which increased outside opportunities for, and the cost of retaining, successful named managers.