From today's Bank nifty movement, I can explain Dow theory's 2 tenets.
1. The market discounts everything.i.e The market reflects all available information. Price shows the market participants mindset.
2. Indices must confirm each other. i.e In order for a trend to be established, major indices(Nifty and Bank Nifty)must confirm each other.
Friday Bank nifty has formed bullish flagpole. A flag is a small rectangle pattern that slopes against the previous trend or a rectangle(This is the example of first tenet as it indicated bank nifty is bullish). Today it broke the flagpole and it is in the process of forming another bullish flagpole. In that case it will retrace a little. Even though Nifty has shown bearish signal on friday,
it didnt give good movement today as bank nifty is bullish(This is the example of second tenet).
Unless Nifty and Bank Nifty move together strong trend wont form.