Contagion? What contagion?

THE financial crisis of 2008 mowed down banks in America and Europe with equal abandon. Not so this year's upheaval. European banks, struggling to fund themselves, are tightening credit. American banks are eager to lend, albeit not to Europe. Their loan growth this quarter will the fastest since mid-2008, reckons Nomura, a bank.

This is partly because America's banks are reasonably healthy. They have significantly bolstered capital since 2008 and now boast core capital of 9% of assets, well above regulatory requirements. While many European banks held dangerous quantities of American mortgages in 2008, American banks today have relatively little exposure to Europe's troubled sovereigns. For the five biggest, total exposure to Greece, Ireland, Italy, Portugal and Spain (net of hedges) ranges from $16 billion at Citigroup, or 14% of core capital, to $2.5 billion at Goldman Sachs, or less than 5%, according to Peter Nerby of Moody's, a credit-rating agency. (But if France gets into trouble, that would be a far bigger problem.)

Yet the least appreciated virtue of America's banking system is that it is drowning in dollars, the byproduct of the Federal Reserve's efforts to kickstart the economy through “quantitative easing”. The Fed has bought government and mortgage bonds to push their prices up and yields down. It pays for them by creating money, which it deposits in the reserve accounts of banks at the Fed. Since late 2008, those reserves have soared from virtually nothing to $1.5 trillion.

America's biggest banks now boast liquid assets of three to 11 times their short-term borrowings, according to Moody's. Despite European banks' well-publicised funding problems, they too have benefited. Lou Crandall of Wrightson ICAP, a research firm, reckons that half of those reserves have ended up with the American subsidiaries of foreign-owned banks. German, Scandinavian, Swiss and French banks all have big holdings. “We're seeing all sorts of strains on markets but no runs on banks because they are sitting on top of huge mounds of cash,” says Mr Crandall.

This seems paradoxical. If European banks hold so many dollars in America, why is a shortage of dollars in Europe driving up LIBOR, the rate at which banks are willing to lend to one another, and prompting deleveraging and asset sales? One reason is that the banks most desperate for dollars are not the ones with big American subsidiaries. Another is that even as European banks deleverage, they are trying to build up their liquidity buffers. And reserves are an attractive vehicle for that: they are one of the world's few remaining risk-free assets, and at 0.25%, they pay more than Treasury bills.

Finally, some banks are clearly liquidating reserves as their private funding dries up. Mr Crandall reckons the reserves of five French banks fell by 22% between June and September, to a still generous $74 billion. This has helped to cushion America from the ill effects of deleveraging at European banks. Nomura notes that European banks' American subsidiaries have begun to shrink their securities holdings but, so far, not their loan books. Nomura figures loans will soon follow, but American banks will benefit as they fill the void.

While America has largely escaped spillover from Europe's banking squeeze so far, the shortage of dollars in Europe remains a problem. To relieve that pressure, the Fed lends dollars to the European Central Bank via a “swap” line, which the ECB then lends to its banks, for up to three months. Demand, so far, has been low, because of the stigma for any bank that uses the system, and the cost: 100 basis points more than a benchmark overnight rate.

On November 30th the Fed, ECB and other central banks sought to rectify this by lowering the spread to 50 basis points. Stockmarkets soared but the euphoria may not last: illiquidity is a symptom of Europe's crisis, not the cause. As long as sovereigns are at risk of insolvency, their banks are, too. If the euro collapses, the resulting chaos will not spare America's economy, despite the health of its banks.