Anomalies in Finance: Irrationality in the Italian Stock Market

Posted: 14 Nov 2010 Last revised: 16 Nov 2014

Date Written: November 1, 2010


The efficiency of global financial markets has long been a topic of contention for both academics and industry professionals alike. Evidence suggests that most of the time, asset markets do a good job of correctly processing and assimilating information into prices. However, a substantial literature has built up proof which indicates that this is quite often not the case. A wide variety of anomalies and so called ‘effects’ have been documented revealing stock price behaviour that is inconsistent with the predictions of traditional models. These inconsistencies illustrate departures from theory and are unexplainable within the mainstream economics paradigm; conversely, many anomalies can be accounted for using explicit insights from behavioural finance. This study discusses the theoretical debate and investigates whether financial markets are affected by superstition and if so, if this is reflected in asset prices. A new discovery is added to the literature, namely the Friday 17th anomaly; with regard to the Italian MIB Storico index results indicate that in comparison to regular Fridays – which are aggregately positive – returns for Friday the 17th are four times larger and statistically different.

Keywords: Behavioural Finance, Market Efficiency, Stock Market Anomaly

JEL Classification: G14

Suggested Citation

McGuckian, Fergus J., Anomalies in Finance: Irrationality in the Italian Stock Market (November 1, 2010). Available at SSRN:

Fergus J. McGuckian (Contact Author)

Università Politecnica delle Marche ( email )

Piazzale Martelli 8
Ancona, 60121

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