Coming Saturday in Personal Finance Focus

By definition, sector funds invest in narrow slices of the market. So it stands to reason that they shouldn't grow too big in size. In fact, conventional wisdom says that when sector-fund asset levels get too high, performance suffers.

But in this week's Big Screen, Ian McDonald finds some billion-dollar sector funds that are doing just fine. So much for conventional wisdom.

Also coming Saturday in Personal Finance Focus:

• Brian Louis outlines several ways of using options to make bets on how earnings season will impact the markets.

• Mark Ingebretsen's Tools of the Trade column tracks down Web sites where you can do due diligence on your REIT investments. (REIT stands for real estate investment trusts, by the way.)

• Tracy Byrnes who inaugurated her new Investor Forum column on Tuesday with a discussion of mutual fund distributions, has more to say about them in Saturday's edition.

We'll also have the regular weekly roundups of best- and worst-performing mutual funds and exchange-traded funds, Stock in the Spotlight and Jim Cramer's regular mutual fund column. See you Saturday.