A longtime reader (and friend) today forwarded me a chart from a well-known technical analyst showing the recent correlation between TIPS (via the TIP ETF) and gold; the analyst also argued that the rising gold price may be boosting TIPS. I've replicated the chart he showed, more or less (source: Bloomberg).
Ordinarily, I would cite the analyst directly, but in this case since I'm essentially calling him out I thought it might be rude to do so! His mistake is a pretty common one, after all. And, in fact, I am going to use it to illustrate an important point about TIPS.
The chart shows a great correlation between TIPS and gold, especially since the beginning of the year. But here's the problem with drawing the conclusion that rising inflation fears are boosting TIPS – TIPS are not exposed to inflation.
Bear with me, because this is a key point about TIPS that is widely misunderstood. Recall that nominal interest rates represent two things: first, an amount that represents the return, in real terms, that the lender needs to realize in order to defer consumption and instead lend to the borrower. This is called the real interest rate. The second component of the nominal interest rate represents the compensation the lender demands for the fact that he will be paid back in dollars that (in normal times) will be able to buy less. This is the inflation compensation.[1]Irving Fisher said that nominal interest rates are approximately equal to the sum of these two components, or
n ≈ r + i
where n is the nominal interest rate, r is the real interest rate, and i is the inflation compensation.[2]
In a world without TIPS, you can only trade nominal bonds, which means you can only access the whole package and nominal interest rates may change when real rates change, expected inflation changes, or both change. (And when interest rates are negative, this leads to weird theoretical implications – see my recent and fun post on the topic.) Thus changes in real interest rates and changes in expected inflation affect nominal bonds, and roughly equally at that.
