* Berkshire adds to Wells Fargo, GM; slashes Kraft, Mondelez
* Some investments kept confidential
* Suncor shares rise after Berkshire reveals stake
By Jonathan Stempel and Tanya Agrawal
Aug 15 (Reuters) - Berkshire Hathaway Inc reported new stakes in Suncor Energy Inc and Dish Network Corp as the company run by Warren Buffett added billions of dollars of stock investments.
The changes were disclosed in a U.S. Securities and Exchange Commission filing made public on Thursday, which detailed $89 billion of Berkshire equity investments, mostly listed on U.S. exchanges, as of June 30.
U.S. regulators require large investors to disclose their stock holdings every quarter, and the disclosures can offer a window into their strategies for buying and selling stocks.
Berkshire took a 17.8 million-share stake in Calgary-based Suncor, which is Canada's biggest oil and gas producer and has a large presence in the Alberta oil sands. That stake was valued at $524 million at the end of the second quarter.
It also reported a small, 547,312-share stake in Dish, the satellite TV company run by billionaire Charlie Ergen, valued at $23.3 million on June 30.
Suncor spokeswoman Kelli Stevens declined to comment, saying the company does not typically discuss individual investors' holdings. Dish spokesman Bob Toevs also declined to comment.
Shares of companies often rise after Berkshire discloses sizable new investments because investors try to copy Buffett, the world's fourth-richest person according to Forbes magazine.
In afternoon trading, Suncor shares were up 68 cents, or 2 percent, at C$34.47. Dish shares were down 29 cents at $44.47.
David McColl, a Morningstar Inc equity analyst in Chicago, said a shortage of pipelines has forced Suncor and rivals to move more products by rail, but that Suncor has indicated an ability to address this problem in the next one to five years.
"Suncor is one of the most heavily undervalued Canadian integrated oil producers," he said. "It is no surprise that a value investor like Berkshire Hathaway would view it as a phenomenal investment opportunity."
Berkshire has benefited this year from Buffett's preference for investments in businesses and stocks over fixed income, which has been under pressure from rising interest rates.
The Omaha, Nebraska-based company's book value per share, Buffett's preferred measure of growth, grew 7.6 percent from January to June.
Its largest stock holding, Wells Fargo & Co, grew 1.1 percent in the second quarter to 463.1 million shares, equal to a $19.1 billion stake in the fourth-largest U.S. bank.
Berkshire spent $4.64 billion on stocks in the quarter. While Buffett has said he makes Berkshire's largest investments, some investments are made by portfolio managers Todd Combs and Ted Weschler, who oversee several billion dollars each.
Thursday's filing did not say who bought what, but said that some holdings were reported confidentially to the SEC.
Buffett sometimes gets SEC permission to amass big positions quietly so he need not worry about copycat investors. One of Berkshire's top holdings, a $13 billion stake in International Business Machines Corp, was built in this manner.
Earlier this month, Berkshire said it ended June with $101.9 billion of equity securities overall. Its top four holdings - Wells Fargo, Coca-Cola Co, IBM and American Express Co - were worth more than $59 billion as of June 30.
Berkshire also owns more than 80 businesses in such areas as insurance, railroads, utilities, chemicals, apparel and food.
In recent months, it bought half of ketchup maker H.J. Heinz Co and made several smaller acquisitions.
On Wednesday, its HomeServices of America Inc unit, the second-largest U.S. full-service residential real estate brokerage, said it bought real estate service companies Prudential Fox & Roach and Trident Group for undisclosed prices.
During the quarter, Berkshire added to stakes in Bank of New York Mellon Corp, automaker General Motors Co, oilfield equipment provider National Oilwell Varco Inc, US Bancorp and Verisign Inc, which assigns Internet protocol addresses. The GM share stake grew 60 percent.
Berkshire slashed its stakes in food companies Kraft Foods Group Inc and Mondelez International Inc by 88 percent and 92 percent, respectively, and shed its stake in newspaper and broadcasting company Gannett Co.
It also reported lower stakes in drugmaker GlaxoSmithKline Plc and credit rating company Moody's Corp.
The SEC filing was to have been made public on Wednesday, but the release was delayed by a glitch in the regulator's filing system. An assistant to Buffett said Berkshire submitted the filing prior to Wednesday's deadline.
In afternoon trading, Berkshire's Class A shares were down 1.2 percent at $172,711, and its Class B shares were down 1.3 percent at $115.08.