Why do we examine calendar anomalies only in financial markets? Month effect evidence from the Greek banking industry

Calendar anomalies (CAs) have been puzzling financial economists and practitioners for decades. The existence of CAs violates one of the most significant financial theories: the efficient market hypothesis (Fama in J Finance 25:383–417, 1970). Up to date most financial economists have examined the existence of CAs only in capital markets. However, as most scholars suggest, an economy’s financial structure includes two main distribution channels: financial markets and financial intermediaries. Therefore, a question that emerges is why do we examine the CAs only in financial markets? Banks are the most important amongst the financial intermediaries; therefore in this study we try to implement the CAs approach to banking. We present the theoretical framework and analytically explain how we apply this approach to banking. In order to examine whether CAs exist we implemented this newly suggested approach in the Greek time deposits market during the period 2003–2013 and we provided empirical evidence for a month effect pattern. The CAs existence: (1) is an indication of market inefficiency, (2) it could be an indirect way to conclude the window dressing (WD) implementation, which is a way to increase the bank opacity, (3) documents a new calendar effect, and (4) may suggest a new approach to the banking efficiency study. Moreover, CAs could be linked to bankers’ WD behavior, ‘forcing’ them to increase the new offered bank premiums at the quarters’ end, in order to attract more deposits.