Anomaly-identification followed by trading strategies shrank the anomalies themselves

Evidence

The case for the Barnesian performativity of the efficient-market hypothesis seems stronger than for the performativity of the Capital Asset Pricing Model. The hypothesis provided a systematic framework within which researchers identified “anomalies”: market phenomena at variance with the hypothesis. Most of those researchers had an efficient-market viewpoint, and many were Ph.D. students at the University of Chicago’s Graduate School of Business, where Fama had formulated the hypothesis and where support for it was strong. Once anomalies were identified, they were often made the object of trading strategies that, in general, seem to have had the effect of reducing their size or even of eliminating them. — Donald MacKenzie, An Engine, Not a Camera, 1151

Categorization

• DEEPTHINKING: The core performativity mechanism — the theory’s anomaly-framing created the trading that eliminated the anomalies it identified — is the thesis’s strongest exemplar, self-correcting in structure.
• XREF: connects to: Accumulating anomalies pointed toward a Kuhnian revolution in finance — Donald MacKenzie, An Engine, Not a Camera: How Financial…, 426; Market anomalies shrink once identified, partly because traders exploit them. — Donald MacKenzie, An Engine, Not a Camera: How Financial…, 433; The index inclusion anomaly undermines the advice to invest in index funds — Donald MacKenzie, An Engine, Not a Camera: How Financial…, 461 (+1 more)

Broader Connections

• Arbitrage erodes the profitability of exploiting the index inclusion anomaly #exemplifies (0.92) — Donald MacKenzie, An Engine, Not a Camera, 462