Ahh. True enough, but a narrow one to be sure, (Made up of only 24 banks and lenders). Point remains that it was hand picked from a sector that is doing historically bad right now in order to try to prove a dubious point.
This is not dubious. People don't have a plan for asset allocation when developing individual portfolios.
Like I said in the post, if you've want 5% of your assets exposed to banks, and the etf doubles, then your exposure is now 10% of your portfolio. You should start paring off to reduce your risk to that particular industry.
Even with broad based index funds aren't completely diversified. There's no hedging against currency, inflation, and taxes (i.e. muni bonds).
If you are to build a passive portfolio, get a friend that works in the High Net Worth section of a broker and get the allocation sheet from them. There's an ETF for every category.