Not even Warren Buffett was immune to the stock market’s rampant first-half gyrations, as Berkshire Hathaway Inc. (BRK.A, BRK.B) notched its worst first half in 18 years, with the shares skidding more than 16%. But only a fool would count out the great Oracle of Omaha, who has spent the past several months restructuring his company’s portfolio and is now ready to come out swinging for the year’s second half.

As Money Morning’s Horacio Marquez noted in his most recent “Buy, Sell, or Hold” feature, Berkshire Hathaway has had a tough start for the year.

The company’s net earnings for the first half were $3.8 billion – a 33% decline from the $5.7 billion reported for the same period last year. But even though the second quarter was weak – especially by Buffett’s standards – it showed marked improvement from the first three months of the year.

Berkshire reported about $1.6 billion in unrealized losses from derivatives in the first quarter. But after warning that derivatives contracts will often “swing wildly,” the company posted $689 million in derivatives gains in the second quarter.

Berkshire’s revenue actually rose 10% to $30.09 billion for the quarter.

But that’s not enough for Buffett, who has set about restructuring his company’s holdings. In the past few months, Berkshire has reduced its investments in Anheuser Busch Cos. (BUD) and Trane Inc., and added positions in NRG Energy Inc. (NRG), Ingersoll-Rand Co. Ltd (IR), and Sanofi-Aventis (ADR: SNY).

According to filings with the U.S. Securities Exchange Commission (SEC), Berkshire in June reduced its stake in Anheuser Busch to 13.85 million shares, less than half the 35.56 million shares it held as of March 31. It’s likely the company received a tidy sum for its shares, as earlier that month InBev SA (PINK: INBVF) offered $65 a share for the American icon. Buffett admits to bailing on the Bud brand before InBev raised its offer to $70 a share, but AB was trading at close to $62 a share on June 30, much higher than the $47 a share the company was valued at in late March. 

Also in March, Berkshire dumped its 10.9 million shares of Trane Inc. That stake was valued at more than $500 million as of March 31.

After unloading in the spring, Buffett treated Berkshire Hathaway to a $4 billion shopping spree over the next several months. By the end of the second quarter, Berkshire’s stake in French drug maker Sanofi Aventis had shot up 317,200 shares to reach 3.9 million.