Unpacking Correlation

The math of ‘bond-equity correlation' is complicated. Our head of Corporate Credit Research breaks it down, along with the impact of bond rates on other asset classes.

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Welcome to Thoughts on the Market. I'm Andrew Sheets, Head of Corporate Credit Research at Morgan Stanley. Along with my colleagues bringing you a variety of perspectives, today I'll be talking about why the same factors can have different outcomes for interest rates and credit spreads.

It's Friday, April 12th at 2pm in London.  

Most of 2024 remains to be written. But so far, the financial story has been a tale of two surprises. First, the US Economy continues to be much stronger and hotter than expected, with growth and job creation exceeding initial estimates. Then second, due in part to that strong economy, interest rates have risen materially, with the yield on the US 10-year government bond about half-a-percent higher since early January. 

More specifically, market attention over the last week has refocused on whether these higher interest rates are a problem for other markets. In math terms, this is the great debate around bond-equity or bond-spread correlation, the extent to which assets move with bond yields, and a really important variable when it comes to thinking about overall portfolio diversification. 

But this somewhat abstract mathematical idea of correlation can also be simplified. The factors that are driving yields higher might look very different for other asset classes, such as credit. That could argue for a different correlation. Let’s think about how.

Consider first why yields have been rising. Economic data has been good, with strong job growth and rising Purchasing Manager Indices or PMIs, conditions that are usually tough for government bonds. Supply has been heavy, with the issuance of Treasuries up substantially relative to last year. The so-called carry on government bonds is bad as the yield on government bond yields is generally lower, much lower, than the yield on cash. And the time-of-year is unhelpful: since 1990, April has been the worst month of the year for government bonds.

But take all those same things thought the eyes of a different asset class, such as credit, and they look – well – different. 

Good economic data should be good for credit; historically, low-but-rising PMIs, as we’ve been seeing recently, is the most credit-friendly regime. Corporate bond supply hasn’t risen nearly as much as the supply for government bonds. The carry for credit is positive, thanks to still-steep credit curves. And the time of year looks very different: over that same period since 1990, April has been the best month of the year for corporate credit – as well as broader stock markets.

Government bonds are currently being buffeted by multiple headwinds. Hot economic data, heavy supply, poor yields relative to cash, and unhelpful seasonality. The good news? Well, Morgan Stanley’s interest rate strategists expect these headwinds to be temporary, and still forecast lower yields by year-end. But for other asset classes, including credit, it’s also important to note that that same data, supply, carry and seasonality debate – fundamentally look very different in other asset classes.

We think that means that Credit spreads can stay at historically tight levels in April and beyond, even as government bond yields have risen.

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