The past week's data-point-of-consequence for investors had to be investment decisions by Warren Buffett's Berkshire Hathaway (BRK.A).

Buffett ended positions in several stocks in the fourth quarter, including the Bank of America (BAC), Nike (NKE), Fiserv (FISV), Becton Dickinson (BDX), Comcast Corp. (CMCSA), Lowe's Co.s (LOW), Nalco (NLC) and Nestle (NSRGY), according to a filing, The Wall Street Journal reported.

Berkshire added to a holding of only one stock in the fourth quarter: Wells Fargo (WFC).

"Berkshire Hathaway's Warren Buffet is a disciple of the teachings of Benjamin Graham and David Dodd, who made their fortunes by buying businesses that were selling for less than the value of their working capital (current assets minus current liabilities," notes Vita Nelson.

The editor of The Moneypaper explains, "The pair developed a Net Current Asset Value (NCAV) model to determine if a company was worth its market price. Their formula subtracts all liabilities, including short-term debt and preferred stock, from a company's current asset balance"

Here's the latest PM dose of happy doom. Tyler over at ZeroHedge points out that CDS (credit default spreads) on Berkshire Hathaway are hitting all time highs, implying that the risks Berkshire's (NYS: BRK.B) robust cash machine could break down (and even default at some point) are rising fast. Piqqem Sentiment on Berkshire B-class shares is negative, natch, after Buffett's recent mea culpa for losing money last year. If Buffett has lost his mojo, then does anyone have any magic left?

"Warren Buffett's Berkshire Hathaway revealed a new position in Nalco Holding (NYSE: NLC); it's my favorite pure play on water filtration," says Chris Mayer in Daily Wealth.

"With a $1.6 billion market cap, Nalco is a small-cap stock, but it's actually one of the world's largest water-treatment companies. Customers use Nalco's products and services to prevent corrosion, contamination, and the buildup of harmful deposits.

"Buffett picked up 8.7 million shares. That makes Berkshire the second-largest shareholder in the company, with a little more than 6% of the shares.It's easy to see what Buffett likes.

With Warren Buffett in the news recently, it is timely to look at a recent report from Paul Tracy, highlighting some of the best-positioned stocks currently held by Berkshire Hathaway (NYSE: BRK.A) -- Burlington Northern Santa Fe (NYSE: BNI) and WABCO Holdings (NYSE: WBC).

Here, the editor of StreetAuthority Market Advisor explains, "Buffett looks for such factors as intrinsic value, low debt, managerial expertise, a margin of safety and an 'economic moats' that offers some sort of sustainable competitive advantage." Here's a pair of transportation stocks that fit the bill.

"While many investors fret over the current volatility in the stock market, Warren Buffett is likely busy looking for value. Historically, in volatile up and down markets, Buffett has found even more opportunities than in raging bull markets."

"Burlington Northern Santa Fe is the second-largest railroad in the U.S. Berkshire holds an 18.2% stake in BNI, recently boosting that stake by purchasing 11 million shares to bring its total ownership to more than 63 million shares. Buffett has made no secret of his desire to purchase more of the stock.

"The key to discerning competitive advantages between the major railroad firms lies in the strategic location
of their networks. Specifically, BNI has the largest network of track in a region of the western U.S.
known as the Powder River Basin, which is home to America's largest reserves of coal.

For 25 years, Steven Halpern, editor of TheStockAdvisors.com, has surveyed the leading financial newsletter advisors asking for their favorite stocks for the coming year. This article is one of 100+ ideas in the Best Stocks for 2008 report.

"What's not to like about PepsiCo (NYSE: PEP) these days?" asks John Reese, editor of Validea, who has chosen the stock as his top conservative idea for 2008.

At Validea -- his quantitative advisor service based on following the strategies of leading market gurus such as Peter Lynch and Warren Buffett -- Reese says, "The beverage and snack giant owns several star American brands (including its famed cola, Doritos, Tropicana, Gatorade, and Quaker Oats).

"The company has a foothold in a bunch of emerging markets with booming economies, and its environmentally conscious streak earned it the No.1 ranking on the Environmental Protection Agency's 2007 corporate 'Green Partners' list.

"As if all that's not enough, the firm's exceptional fundamentals garner approval from the 'Guru Strategy' computer models that I base on the approaches of two legendary investors -- Warren Buffett and Peter Lynch.