I want to see if I can explain Zak's ideas in a little greater detail. Basically, he's right.
To recap, the original NGDP futures targeting idea goes something like this:
1. The Fed sets an NGDP target (say, 5%).
2. The Fed then offers to enter into any number of NGDP futures contract with anyone who wants, at a price equal to the target. So if I take a $1000 long position in these futures, and NGDP comes in at 10% (double the target), I get $2000 back. If I take a $1000 short position, and NGDP comes in at 2.5% (half the target), I get $2000 back. And so on. The Fed is always on the other side of the deal, and I can make as many of these deals as I want (assuming I can post sufficient margin).
3. The Fed then makes monetary policy automatically in response to people entering into these contracts with it. If a person takes a long position in NGDP futures, the Fed tightens a bit to make sure NGDP doesn't actually come in above target.
Zak had three main criticisms of this idea:
A) Informed traders will not trade in this market,
B) Manipulators will trade in the market, and
C) Data revisions will introduce noise into monetary policy.
I'll ignore (C) and try to explain (A) and (B). Keep in mind that I'm not saying anything new in this post; just restating Zak's argument in my own words.
First, let's talk about why informed traders - the people we want to trade these contracts - won't even show up. Suppose I have some knowledge that the Fed doesn't, about macroeconomic forces. For example, suppose I see a big inflationary shock coming that, if the Fed doesn't counteract it, will raise NGDP to 10%. Will I take a long position in an NGDP futures contract in the market described above, thus revealing my private information to the Fed and helping it make better policy?
It depends. IF the Fed hits its NGDP target on average, then I will not. Because in that case, on average, I would lose money betting on the Fed not hitting its target. Why the heck would I bet good money on 10% - or 2%, or 6%, or 5.001% -- when the probability distribution of NGDP is distributed symmetrically around 5%? A negative expected return with positive risk? No thanks!
If the Fed DOESN'T hit its target on average, then I might be able to make some money entering into this futures contract. But if the NGDP futures targeting mechanism doesn't lead to the Fed hitting its target on average, why the heck would we want to use that mechanism to make monetary policy in the first place??
So IF the mechanism works, no informed traders would use it. Hence, whatever information they have about macroeconomic shocks will NOT reach the Fed.
That is criticism (A).
OK, so who definitely would trade in that futures market? Manipulators.
Suppose I'm just some deep-pocketed jerk with zero knowledge of the macroeconomy, and I want to make some free money at the expense of the country and the bond markets. Here's what I do. First, I sell TIPS and buy Treasuries - in other words, I bet against inflation. Then I take a huge amount of long positions in NGDP futures. The Fed tightens monetary policy. My TIPS go down relative to my Treasuries, and I pocket the spread. Then I take a bunch of short positions in NGDP futures -- at the exact same price as before -- to net out my previous long position.
I have manipulated the TIPS and Treasury bond markets. I have caused monetary policy to change. And I have made arbitrage profits.
This is bad, because it introduces noise into monetary policy, and it also causes the bond markets to be less efficient.
That is criticism (B).
Both of these criticisms are valid. In other words, an NGDP futures targeting policy as stated above would introduce zero information to the making of monetary policy, while introducing a nonzero amount of noise. You'd be better off setting monetary policy according to a random number generator, because at least then you wouldn't be letting crooks rig the bond markets.
So Zak David is correct. The idea is not sound. If you want to use NGDP futures targeting to set monetary policy, you're going to have to think of a much better system than the one described above.
(Fun bonus point: Why doesn't criticism (A) apply to all financial markets? That's probably the biggest question in the field of market microstructure. Check out the Glosten-Milgrom model and the Kyle model for two classic answers to that question.)
1. Everybody is asking me to link to these old posts (post 1, post 2) by Mike Sankowski criticizing Sumner's idea. Check them out if you're interested in this debate (and if you're not, why have you read this far?).
2. As expected, Scott Sumner fires back. He accuses Zak and me of disbelieving the EMH. Well, does anyone think the EMH holds when the government pegs the price of assets? If the government offered to buy and sell infinite amounts of Tesla stock futures at the price of $200 a share, would that market be efficient? No, it would not. Would $200 be the best estimate of Tesla's future earnings? No, it would not. Scott, just because you call something a "market" doesn't mean it's efficient.
Sumner seems to have thought very little about how markets actually become efficient. Scott, you need price discovery. Which means you need informed traders to trade. Informed traders' trades are the mechanism by which information gets from the world into the price. If informed traders don't trade, the price is based on some combination of A) noise, and B) manipulation. Informed traders only show up if they can profit by trading on their information. For informed traders to profit, someone else must lose money. In most models of market microstructure, the money is lost by liquidity traders (sometimes called "noise traders", though that term is now usually used to mean fools who trade overconfidently on false information).
In Sumner's "market", the only liquidity trader is the Fed itself. If the Fed sets policy such that A) informed traders can make money trading against the Fed, and B) the Fed offers infinite liquidity, that means that informed traders can make infinite money at the Fed's expense. But the Fed controls policy. It can make very, very, very sure it does NOT lose infinite money to informed traders. If the Fed provides infinite liquidity, the only way for the Fed to make sure that it doesn't lose infinite money to informed traders is for the Fed to make sure it doesn't lose any money to informed traders. (Note that this would most likely involve setting monetary policy to overreact to any trade.)
Hence, an informed trader would have to be dumb to trade in Scott's market, because trading in Scott's market means fighting the Fed and losing. Hence, no informed traders will show up. So the only traders who do show up will be A) liquidity/noise traders, B) fools, and C) manipulators. Hence, if the Fed sets monetary policy in reaction to trades in Sumner's market, it will set monetary policy purely in reaction to noise and/or manipulation.