This week, we got a glimpse into what stocks Warren Buffett's Berkshire Hathaway was buying and selling in the third quarter.

There were some surprises, mainly that the firm only added US$100 million to its Apple stake and instead deployed almost $14 billion to buy shares of several financial services firms while also taking a new $2 billion stake in Oracle.

Of the stocks added to in the quarter, Morningstar's equity analysts think that four are undervalued, trading in 4-star territory today.

Those are wide-moat Bank of New York Mellon, no-moat General Motors, narrow-moat Goldman Sachs, and narrow-moat Travelers Companies.

On the sales side, Berkshire exited out of stakes in Walmart and Sanofi while also shedding some shares of Phillips 66, Wells Fargo, Charter Communications, and several airlines.