Writing in The Times (London) today, Anatole Kaletsky reminds us that “the financial hurricane season” is now upon us.

“Nearly all the greatest financial accidents — the Wall Street crashes of 1929 and 1987, Nixon’s closure of the Bretton Woods gold window in 1971, the Asian currency crisis of 1997, the Mexican and Russian defaults, the attack on the French franc in 1993, the sterling devaluations of 1949, 1976 and 1992 — have occurred between late August and October”.

On Wall Street buyers generally hold off until Hallowe’en, on October 31, while selling is automatic for various reasons: “…selling of equities is partly a passive phenomenon, since portfolios have to be liquidated when their owners die or cash retirement cheques or make insurance claims.

“These liquidations happen steadily through the year, regardless of seasons. Buying, on the other hand, requires conscious decisions and investors are less likely to make these when they and their brokers are away on holiday.”

So the next couple of months will be crucial for financial markets. Have yourself a safe financial hurricane season.

LSE Latest reports that The New York Stock Exchange has signed a $20 billion (£10.7 billion) merger agreement with Euronext, the conglomerate of European exchanges, in an historic deal to create the world’s biggest stock exchange.

The combined business will become the world’s first transatlantic exchange: NYSE Euronext, at a ceremony in Paris this afternoon, chosen to demonstrate that it’s a merger of equals, not a takeover.

However, Thomas Caldwell, whose company owns 4.3 million NYSE shares, told The Times (London) that “the international nature of the deal might fall foul of politicians worried by foreign takeovers of key US businesses”.

John Thain, NYSE chief executive, will become CEO of the proposed combine, the headquarters of which will be on Wall Street. Jan Michel Hessels, Euronext’s supervisory board chairman, will be the new chairman.

A Euronext spokesman said: “The balance of the executives will be maintained.” A Euronext director could take over the CEO role when Thain retires, he implied.

NYSE and Euronext shareholders must still vote on the merger.