Liquidity Preference as Behavior toward Risk Is a Demand for Short-Term Securities-Not Money
质疑托宾的流动性偏好理论，指出短期货币市场工具作为无风险且付息的货币替代品，使该理论失去现实基础，并分析了储蓄存款和定期存款的局限性。
In 1958, James Tobin generalized the Keynesian theory of liquidity preference by means of his famous portfolio model in which the demand for money (narrowly defined) is treated as behavior towards [interest] risk. Whatever merit this theory may have had then has long since been questionable. The reason is the existence of a large set of substitutes for money, typically short-term money market instruments, which can be regarded as riskless, or virtually so, and which pay substantial interest. The availability of these instruments would appear to make Tobin's theory that money is held to cope with interest risk resemble a scenario without a recognizable cast of actors. In the literature on monetary theory, other authors have also expressed misgivings about the Tobin theory by noting that savings and (nontransferable) time deposits have the same risk properties as money but pay interest (see, for example, Robert Barro and Stanley Fischer, 1976). Although correct, the allusion to these deposits is simplistic. It is true that while both types mimic money's freedom from interest risk in the conventional sense of capital loss, time deposits are still exposed to a kind of interest risk, because they can be liquidated before maturity only with interest penalty. More important, business firms are either denied access to savings deposits or, as in the United States, can hold a maximum of $150,000 (per account) at commercial banks, thereby effectively eliminating large firms as holders. Furthermore, although business firms can own most time deposits, they typically do not (except for negotiable CDs, a money market instrument); they are loath to tie up funds in long-term maturities, and they can usually obtain the same or higher yields on other types of short-term debt instruments that are also negotiable. In the United States, households have long accounted for about one-third of demand deposits, business firms owning most of the rest. Therefore any effort to rest a case against the Tobin theory of money demand on the existence of savings and time deposits gets at only a small part of the problem. This stricture extends to so-called NOW and ATS accounts. These interest-bearing demand deposits (disguised under other names) are also denied to business firms. For them, the short-term instruments of the money market are the principal alternative to money in asset portfolios.