Legendary investor, Warren Buffett — the Sage of Omaha — in a move he says is designed to make money, has offered to take on $800 billion of the liabilities of U.S. municipal bonds.

The offer goes to three “monoline” bond insurers, Ambac Financial, MBIA and Financial Guaranty Insurance. One has already rejected the deal, and he is still awaiting reponses from the other two, although one of them is making favourable noises.

The move breathed new life into global stock markets yesterday. The monolines are seen as the second line of defence against the sub-prime mortgage fiasco by propping up banks’ balance sheets in the event of a repayment meltdown.

Traditionally, the bond insurers concentrate on municipal risk, but they too got caught up in the collective madness of sub-prime lending for the same reason respectable banks did : greed for perceived easy money.

However, the monolines are now short of capital and are being hit by downgrades from the rating agencies.

T J Marta, fixed income strategist at RBC Capital Markets, said it was a coup for bond insurers, which could help them avoid “the doomsday scenario”.

It’s a phrase we hear all the time, Sub-Prime, usually associated with the worldwide credit crunch now current across the mortgage market. But where did it come from?

Some historians think it can be traced back to the Old West and the vast cattle markets of of Chicago and Nebraska. Traders labeled the finest cuts of meat as “prime” and the lesser cuts “choice” — something of a euphemism, obviously.

However, “choice” was usually translated in buyers’ minds as “sub-prime”, that is, something no-one really wanted.

Then “prime” was adopted by American bankers to describe rates charged to their most creditworthy customers. All others became “sub-prime”.

British banks apparently have more fruity terms. What in the States is called “sub-prime” is in England labeled a “lemon”.

There are a lot of lemons around just now.

Once again the housing market is in the financial news as it threatens to disrupt the rest of the American economy.

US Treasury Secretary Hank Paulson issued the warning following a two-day meeting of the G20 — the world’s 20 most industrialized economies.

Paulson said there would be continuing volatility in financial market because the sub-prime mortgage crisis is still unfolding. He insisted, however, that the US economy remains “healthy and diversified” and will continue to grow.

The G20 finance ministers agreed there was too much volatility in currency values — a dig at the precipitate fall in the dollar — but fell short of criticizing the weakness of the greenback.

This story will run and run.

The collapse of the American sub-prime market, with all its attendant woes, both to borrowers and lenders, really hit home yesterday.

The European Central Bank, regulator of the Eurozone group of countries, piled into the markets with $130 billion of cheap, emergency credit.

In what was the biggest central bank intervention since 9/11, the ECB move came after reports that commercial lenders were desperately hauling back the supply of loans.

French giant BNP Paribas suspended withdrawals from three of its investment funds because of their exposure to the U.S. sub-prime market, saying “There has been a complete evaporation of liquidity” from credit markets, which could escalate into a worldwide credit squeeze.

Rumours were rife of impending fund meltdowns and banking collapses. Trevor Williams of Lloyds TSB said, “Liquidity has dried up basically. It’s a moment of panic.”

Nick Sparks, risk manager at F&C Partners, said, “People have got caught out. There will be more pain to come.”