Across Asia, regional markets are mostly lower after credit rating agency Moody's said after hours that the United States' triple-A credit rating is under review for possible downgrade. This has seen widespread caution throughout Asia, with the Kospi and Hang Seng the worst performers, down 0.8% and 0.7%. The Nikkei 225 is softer by 0.6% while the Shanghai Composite is showing modest gains of 0.1%.

In Australia, the ASX 200 is currently down 1% at 4468, right on its lows of the session. Despite the modestly higher close on Wall Street overnight a threat by Moody's to downgrade the US credit rating has spooked investors into lightening positions. The heaviest losses are being felt across the information technology, consumer discretionary and financial sectors. Elsewhere, the materials and energy sectors are only marginally lower courtesy of a weaker USD helping boost overnight commodity prices.

Once again, we're seeing more weakness in the local market. Markets globally don't seem to be able to take a trick at the moment. Half way through the overnight session it looked very positive, with the major indices all up more than 1% following comments from Fed chairman Ben Bernanke that the Fed would provide further stimulus to the economy if it needed it.

US Debacle

However, stocks began to lose ground in the latter part of the session as news filtered through that the Democrats and Republicans were getting nowhere in their 'debt ceiling' debate and another Fed board member came out and said they do not see the benefits of further stimulus for the economy.

Then, to top it all off Moody's said after the closing bell that the US credit rating had been put on review for possible downgrade. Moody's followed the lead of Fitch and S&P, who moved weeks ago. It was hardly a surprise, although the markets reacted that way.

After the subprime debacle, these credit agencies are acting as if they have something to prove to everyone by downgrading everything in sight. We wonder how much credibility they have following their stellar GFC performance!

Nonetheless, it appears the storm clouds have formed on the horizon once again. The market is starting to get quite jittery over the US debt ceiling debate. With each passing day of stalemate discussions, the risk of US default rises which many are now saying could trigger a precipitous plunge in equity markets, possibly in the same vain as the first failed TARP vote (Dow -700 pts overnight).

On top of that, Eurozone concerns continue to bubble away, with the release of the European bank stress tests tomorrow night capable of throwing another spanner in the works. All in all, it's making for a very tough market as sentiment continues to turn on a dime.

(Ben Potter, Market Strategist-- IG Markets)