Discount Markets, Liquidity, and Structural Reform

Bengt Holmstrom has a paper explaining the “diametrically opposite” foundations of money markets and capital markets.* This dichotomy is also a foundation of traditional banking theory, and of the traditional functional separation that was maintained in the U.S. and Britain between money and capital markets.

Holmstrom explains that “the purpose of money markets is to provide liquidity,” whereas price discovery is an important function of capital markets. In a paper I extend this view a step further: money markets don’t just provide liquidity but a special form of price stable liquidity that is founded on trade in safe short-term assets; by contrast capital markets provide market liquidity which promotes price discovery, not price stability.

A century ago in Britain privately issued money market assets were, like capital market assets, actively traded on secondary markets. The two types of assets traded, however, on completely different markets with completely different structures that reflected the fact that money market assets needed to be “safe.”

To understand why the markets had different structures consider this question: how does one ensure that the safety of the money market is not undermined by asymmetric information or more specifically by the possibility that when the owners of money market assets have information that the assets are likely to default they do not use the market to offload the assets, adversely affecting the safety of the market itself, and therefore its efficacy as a source of price stable liquidity? The answer is to structure the market as a discount market.

In a discount market, every seller offers a guarantee that the asset sold will pay in full. (You do this yourself when you endorse a check, signing its value over to a bank — while at the same time indemnifying the bank against the possibility that the check is returned unpaid.) This structure was one of the foundations upon which the safety of the London money market was built. The structure ensures that the owner of a dubious asset has no incentive to attempt to sell it, and in fact is very unlikely to sell it in order to hide from the public the fact that it is exposed to such assets.

From their earliest days it was well-understood that discount markets were designed to align the incentives of banks originating money market assets and to promote the safety of the assets on the money market. (See van der Wee in Cambridge Economic History of Europe 1977.) Any bank that originates or owns a money market asset can never eliminate its exposure to that asset until it is paid in full. For this reason a discount market is specifically designed to address problems of liquidity only. That is, a bank that is illiquid can get relief by selling its money market assets, but if it has originated so many bad assets that it is insolvent, the money market will do nothing to help.

Contrast the structure of a discount market with that of an open market. On an open market, the seller is able to eliminate its exposure to the risks of the asset. This has the effect of attracting sellers (and buyers) with asymmetric information and as a result both increasing the riskiness of the market and creating the incentives that make the prices of the risky assets that trade on open market informative. Thus, it is because price discovery is important to capital markets, that they are structured as open markets. Capital markets can only offer market liquidity — or liquidity with price discovery — rather than the price stable liquidity of the money market. On the other hand, an entity with asymmetric information about the assets that it holds can use the open market structure of capital markets to improve its solvency as well as its liquidity position.

Historically it appears that in order for a money market to have active secondary markets, it must be structured as a discount market. (Does anyone have counterexamples?) That is, it appears that when the only option for secondary trading of money market instruments is an open market, then secondary markets in such instruments will be moribund. This implies not only that the absence of incentives to exploit asymmetric information plays an important role in the liquidity available on money markets (cf. Holmstrom) — but also that price stable liquidity is an important benefit of the discount market structure.

Both discount markets and open markets can be adversely affected by extraordinary liquidity events. But only one of the two markets is premised on safe assets and price stable liquidity. Thus, the lender of last resort role of the central bank developed in Britain to support the money (discount) market only. (In fact, I would argue that the recognized need for a provider of liquidity support to the discount market explains why the Bank of England was structured as it was when it was founded, but that goes beyond the scope of this post. See Bowen, Bank of England during the Long 18th c.) One consequence of the fact that the central bank supported only assets that traded on a discount market is that it was able to support the liquidity of the banks, without also supporting their solvency.

Given the common claim that one hears today that it is unreasonable to ask a central bank to distinguish illiquidity from insolvency in a crisis, perhaps it is time to revisit the discount market as a useful market structure, since acting through such a market makes it easier for a central bank to provide liquidity support without providing solvency support.


*His focus is actually money markets and stock markets, but in my view he draws a distinction between debt and equity that is far less clear in practice than in theory. In a modern financial system unsecured long-term bonds are not meaningful claims on the assets of a firm, because as the firm approaches bankruptcy it is likely to take on more and more secured debt leaving a remnant of assets that is literally unknowable at the time that one buys an unsecured long-term bond.


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