Alphability are Automated Trader's proprietary tradability metrics. They are environmental statistics intended to assist those building trading models/systems in determining which markets and timeframes are most favourably responsive to which generic types of model. For more information on Alphability, please see page 56 of the Q3 2007 edition of Automated Trader or visit http://www.automatedtrader.net/Alphability.xhtm
Figure 1: Daily Trend Alphability - top five Dow stocks
The trend is only your friend if your President also is; which he clearly wasn't in the case of Bank of America on Jan 21st.