The week commenced with investors eagerly anticipating two key events, the EU summit and a Supreme Court ruling on healthcare. Both had surprising outcomes. On Thursday the US top court upheld the constitutionality of the individual mandate, the backbone of President Obama’s Affordable Care Act.

Rollercoaster trading made for highly volatile markets this week. Monday was relatively quiet, with some Asian and all European markets closed for holidays, but the big unwind seen last week continued apace on Tuesday as European traders got their first chance to sell in the cash market following last Friday’s disappointing US payrolls report.

The second quarter of 2012 got off to a sour start this week as market participants appeared genuinely surprised by comments from Fed and the ECB that strongly suggested there would be no more extraordinary stimulus, except in the event of another sharp economic slowdown.

The final week of trading in the first quarter was subdued, as analysts celebrated just how well the stock market performance has been over the last three months. European stocks were had their best quarter since 2009, up 7%, while Japan’s Nikkei index rose nearly 20% in the quarter, for its best performance in 24 years.

The S&P500 snapped a five-week uptrend this week, as poor data in Asia and Europe made for lousy sentiment. Continuing fears about economic slowdown in China got the ball rolling early on in the week, after BHP offered flattish guidance for China iron ore shipments and unsubstantiated rumors of a coup brewing in Beijing made the rounds.

Greece defaulted on its debt this week, bringing to an end a long dramatic chapter in Europe’s continuing sovereign debt crisis. But even as confirmation of the final participation rate in the PSI debt exchange arrived late in the week and the ISDA declared that the exchange constituted a “credit event,” thereby triggering CDS, few have any illusions that this story is over.

Investors watched in amazement this week as the DJIA flirted with 13,000 and many wondered just how much longer the equity rally could last. The Eurogroup has approved the new €130B bailout for Greece, the PSI private debt exchange is ready to run and default armageddon has been postponed for the moment.

Chaos in the streets of Athens dominated the news again this week, as pictures of riot police and burning buildings suggested that Greek society was at the breaking point in the face of austerity.

The Greece bailout negotiations ground on again this week, although markets are displaying a certain amount of numbness to developments in Athens and Brussels. The central issue has been the passage of another round of austerity measures demanded by the IMF and EU as a condition of the next tranche of bailout payments.

In the last few months we have seen some limited positive progress out of politicians who previously seemed determined to fail to the detriment of the economy.