High beta financial stocks

As we discussed numerous times in class Beta is a measure used to see the volatility or tendencty of movement of Stock vs. Market.

Beta of 1 moves perfectly along with the market.
Beta of 2 moves twice as much as the market.
and it is the index represented by S&P index.

When investing in stock market, individuals must think about the return and the risk associated with each of the stocks.
And one technique to increase wealth was to have diversity in our portfolio.
Risk management can show a lot of its value in such category as well.

Now, how much a Beta can grow?
I have searched for high Beta companies online and below are some of the companies.

from business week/

1. Citigroup B= 3.2
2. Office Depot B=3.1
3.Ford B=2.9

These seems very high in Beta.
However, according to website at Schaeffers research,

1.Mercadolibre Inc. B=4.55
2.LMI Aerospace Inc. B=3.82
3.LDK Solar Co. LTD B=3.72

I personally think investors should have a very good understanding of the company if they are going to be investing into any of these companies. I don't know how these companies are more volatile than companies such as Citi or Ford, which it is now in ditress.