Berkshire had about 11 million shares of Goldman Sachs as of Sept. 30, compared with 12.6 million three months earlier, according to a filing Monday disclosing holdings as of the end of the third quarter. The stake in Wal-Mart dropped to 56.2 million shares from 60.4 million.

Buffett agreed in August to buy aerospace-equipment maker Precision Castparts Corp. for more than $30 billion. Standard & Poor’s is reviewing whether to cut Berkshire’s credit rating amid an examination of how Buffett will finance the transaction, which the companies expect to be completed next year. The billionaire told CNBC that he sold some stocks to help pay for the deal, according to a Twitter post from the business news station.

“I’m surprised he had to sell anything to fund the Precision Castparts purchase, with over $60 billion of cash on his balance sheet,” David Kass, a professor at the University of Maryland’s Robert H. Smith School of Business who has taken students to meet Buffett in Omaha, Nebraska, wrote in an e-mail.

‘Good Excuse’

Jeff Matthews, an author of books about Berkshire who previously invested in the company, was also skeptical of Buffett’s justification. Proceeds from selling the Wal-Mart shares were probably less than Berkshire’s dozens of operating businesses make in a week, he said.

“It was a good excuse to trim some stocks that make sense to sell,” Matthews wrote in an e-mail. “Goldman Sachs today operates in a different world than when he bought it during the crisis. And Wal-Mart is under assault from Amazon and not likely to recover.”

Buffett didn’t respond to a request for comment sent to an assistant. A Wal-Mart representative said the company doesn’t comment when an individual or group buys or sells shares. Investors closely watch Berkshire’s filings for clues about Buffett’s investment strategy. His purchases and sales can sometimes move stock prices.

Goldman Sachs rose 0.9 percent to $192.16 in New York on Monday. Wal-Mart climbed 2.6 percent to $57.87.

Kraft Heinz

The biggest additions to Berkshire’s portfolio in the third quarter were previously disclosed. The company said in August that it had boosted its holding in oil refiner Phillips 66 above 10 percent. Berkshire also became the biggest holder in Kraft Heinz Co. in July.

By backing the merger that created the food company, Buffett generated a $4.4 billion windfall for Berkshire. The gain helped overshadow the challenges facing some of his biggest holdings.

One of his recent laggards, American Express Co., still trades well above the average price Berkshire paid for the shares. Wal-Mart is closer to break-even. But a third, International Business Machines Corp., is a different story.

Unrealized losses on Berkshire’s stake in IBM widened to $2 billion as of Sept. 30, or about 15 percent of what Buffett paid. Still, he said in a quarterly filing on Nov. 6 that he has no plan to exit the holding and expects shares to recover. Berkshire disclosed Monday that it added more than 1 million IBM shares in the third quarter.

‘Preferred to Keep’

Buffett agreed in 2008, as credit markets were drying up, to buy $5 billion worth of preferred Goldman Sachs stock that paid an annual dividend of 10 percent. He also got warrants that he later used to get more than $2 billion of the bank’s shares in a cashless transaction.

While Buffett has said his preferred time to hold a stock is “forever,” he is willing to make sales when he finds other opportunities. In the financial crisis, when Buffett won favorable terms in deals that helped prop up companies like Goldman Sachs, he also reshaped Berkshire’s stock portfolio.

“To fund these large purchases, I had to sell portions of some holdings that I would have preferred to keep,” Buffett wrote in 2009 of Johnson & Johnson shares and stakes in Procter & Gamble Co. and ConocoPhillips. “However, I have pledged to you, the rating agencies and myself to always run Berkshire with more than ample cash.”

Credit Rating

S&P put Berkshire on CreditWatch Negative after the Precision Castparts deal was announced in August, citing “uncertainty around the funding of the acquisition and how it may affect current cash resources and leverage metrics at the holding-company level.” The ratings firm said at the time that it could resolve the examination within 90 days, then extend the review this month, possibly for another three months.

Berkshire is rated AA at S&P, the third-highest of 10 investment-grade scores. Buffett said in August that he planned to use about $23 billion in cash for the Precision Castparts deal while borrowing another $10 billion. Berkshire had more than $66 billion in cash as of Sept. 30, but needs to keep a large hoard to cover unexpected costs at insurance operations.

Goldman Sachs and Wal-Mart remain among Buffett’s top holdings. His investment in the bank was worth about $2.1 billion based on Friday’s closing price, while the Wal-Mart stake was valued at more than $3 billion. Berkshire’s largest positions are in Wells Fargo & Co., Kraft Heinz and Coca-Cola Co.

Monday’s filing showed no stake in media company Viacom Inc. as of Sept. 30. That compares with about 5.6 million million shares as of June 30.

Berkshire also reported a new holding in AT&T Inc., valued at about $1.9 billion. Buffett’s deputy investment managers were among the largest holders of DirecTV, which was purchased by the telecom giant in July in a cash-and-stock deal.