At Berkshire Hathaway’s annual meeting last year, Warren Buffett struggled to hide his frustration about how a pliant debt market had helped to lift the prices of many assets beyond what a value investor such as him was willing to pay to acquire them.

The thousands of devoted shareholders making the pilgrimage to Omaha for this year’s “Woodstock for Capitalists” will probably hear Mr Buffett reflect on a much more volatile – and for him, opportunistic – 12 months.

In his annual letter to shareholders of his investment company in March, Mr Buffett took aim at the lenders that had helped bring about the credit bubble and the ensuing crisis.

“You only learn who has been swimming naked when the tide goes out – and what we are witnessing at some of our largest financial institutions is an ugly sight,” he wrote.

After several quiet years, Mr Buffett has in recent months capitalised on the markets’ turbulence to buy companies, invest in undervalued shares and launch his own bond insurer.

This week he agreed to help Mars finance its $23bn takeover of rival Wrigley, the company whose chewing gum Mr Buffett peddled door to door as an Omaha schoolboy.

On tour to meet Europe’s families

Warren Buffett is turning his attention to Europe, a continent he has hitherto avoided, writes Richard Milne in Frankfurt.

He will start a four-country tour on May 19 in Frankfurt before going on to Lausanne, Madrid and Milan.

His goal is to examine the hidden secret of European capitalism: the family-owned companies that dominate the economies of regions such as northern Italy and Germany. People involved in his trip say he will meet some of the biggest such companies in each country, all of which are market leaders in their field.

The impetus for the tour comes from his recent acquisition of Iscar, an Israeli manufacturing company that was his first major purchase abroad.

Flush with cash, Mr Buffett could find many companies in Europe that meet his criteria of being understandable businesses in long-term industries. He will also take part in several events focusing on family businesses with the IMD business school.

Family-owned companies across Europe are renowned for their long-term outlook and often have a much stronger export focus than their US rivals. But many have succession problems – and that is where Mr Buffett and his cash may well come in handy.

Along the way, Mr Buffett overtook Bill Gates, his friend and bridge partner, as the world’s richest person, with an estimated fortune of $62bn, according to Forbes magazine. Shares in Berkshire Hathaway increased by more than 20 per cent in the year ending February 11, Forbes’ cut-off date for its 2008 Rich List.

However, the past year has dealt Mr Buffett’s some setbacks into the bargain.

Joseph Brandon, once considered a leading candidate to replace Mr Buffett at the helm of Berkshire Hathaway, stepped down last month as head of its reinsurance division, General Re.

Mr Buffett had repeatedly praised Mr Brandon’s stewardship of General Re since his appointment as chief executive in 2001. The departure followed the convictions of four former colleagues for fraud. Mr Brandon has not been charged with any wrong-doing. He was identified as a non-indicted alleged co-conspirator in a trial that resulted in the conviction of Ronald Ferguson, the previous chief executive, and three other former executives.

Berkshire came under more direct scrutiny this week when shareholders learnt that Mr Buffett’s holding company was being examined as part of the Connecticut attorney-general’s broad investigation into conflicts of interest in the credit rating industry.

The civil investigation, running for at least six months, concerns potential anti-trust violations involving the main credit rating agencies, Moody’s Investors Service, Standard & Poor’s and Fitch Ratings; bond insurers; and other companies, according to Richard Blumenthal, Connecticut attorney-general.

“We are investigating under anti-trust authority whether conflicts of interests or improper relationships have led to skewed ratings,” he told the Financial Times.

Mr Blumenthal said Berkshire’s ownership of 19.5 per cent of Moody’s, which last week gave a top-notch rating to Berkshire’s newly formed bond insurance business, “certainly creates an appearance of a conflict of interest”. But he said the examination of the relationship was only “a slice” of the investigation.

“We are not making any allegations and we reached no conclusions,” he told the FT.

“We are not challenging any of the specific ratings.”

In his letter to shareholders, the billionaire said he had chosen four unnamed candidates to replace him as chief investment officer of Berkshire when he dies or steps down. Berkshire has a $140bn pool of investments.

The 22-page document – required reading for investors who follow Mr Buffett’s folksy nuggets of wisdom – also warned that Berkshire’s core insurance business faced a tougher future.

The warning appeared to be borne out by Berkshire’s fourth-quarter results, which were down 18 per cent.