"Credit’s Divorce From Stocks Signals End of Rally"??

Interesting "chart of the day" today on Bloomberg: it overlays the S&P500 index with the iTraxx Europe 5Y index (inverted, so that a upward curve also indicates positive performance). The resulting graph shows two curves that look very similar -- until very recently:



The conclusion reached by the strategists who published that graph is that the S&P500 went ahead of itself, as judged by the relative under-performance of the credit index. To quote the press release, "Credit’s Divorce From Stocks Signals End of Rally."

Although I do believe the equity index went ahead of itself, I have issues with the reasoning.

First, we have to be mindful of units: one time series is expressed in S&P points, the other in the inverse of bp; so a more meaningful comparison would be to compare time series of returns (for instance, day-to-day returns).

Second, the time scale is short: their time series begins in early August. If we look at a longer period, we get the graph below. The time frame is still relatively short (we pulled data starting on March 02, 09) but long enough to show that there's been other "credit's divorce from stocks" in recent past:



And third and foremost, how can we tell: Is it S&P500 that's too high, or iTraxx that's too low?? The two indices do have a (relatively short) history of moving in tandem, but there have already been times when the two plots diverged before merging again -- i.e., there have been other "divorces of credit from equity," and they were temporary: None of these instances was followed by an end of the equity rally! On the contrary, the trend has steadily been upward! So I find the technical chartists a bit short on convincing arguments here.